AC Fan Motor Problem

My guess was going to be bearings.

I'd guess it would be dust wear and lack of lubriction....hey you should bring it the pub!

Any way of getting a squirt of WD40 onto the back bearing when it is going slow to see if that eases it off? (Just for checking purposes .. obvoiusly not an actual solution)

Dunno what the bearings are like..if they are 'self aligning' sometimes they get gumked up and don't float freely enought to align and thus bind up.(A gently tap with a mallet may help...it'll certainly make you feel better anyway)

Good luck with it.

Del

That was my first idea Del, I climbed up there oil can in hand figuring I could lubricate the bearings and it would be fine. Unfortunately they are sealed bearings, no way to lubricate them (at least on the outboard. I have not torn things apart enough to get to the fan end bearing).

Mr. Steve, I too had this problem recently and could solve it. Normally such small motors do not have ball bearings, but brass type porous bush, over it sponge type material that is wet with some lubricating oil. In my case I found a small hole for lubricating and I put two drops of oil. Secondly I have tighten four bolts of the fan motor. I though may be after heating up the rotor is touching the stator due to expansion. If you can not try first one try the second.

Presumably it is a commutator motor? A close relative swears by the maxim: "If it doesn't work properly, change the carbon brushes!"

Yeah, but I think I will just change the whole motor.... that will get the brushes too...

after you change the motor rip it apart and tell us what you find.......Please

Try this... After it stalls, grab the blades and try turning them in the opposite direction. Let us know what happens.

...after removing power first Vermin!!!!

A finger count afterwards might be in order.

You might also want to check (assuming this unit uses them) the capacitors in your compressor. I had one go out on me, with the exact symptoms you describe, and it turned out to be one of the motor caps.

I think that this is just further proof that electricity is not to be trusted.

The gentle tap with a mallet after taking it to the pub idea has a lot of appeal and the post-mortem report should be posted. This would serve as a warning to other electrical devices.

Hi

If the motor has a run capacitor that is changing value this will also cause motor problems but most often it s due to bearings.

gval102

If it is the Cap then it would have a start-up problem. I would also say, like the others, it must be the bearing and if it isn't...then it must be a miracle.

If there is a cap and the fan stall after running for a while, then it may be a result of the cap being open circuited after being warmed up. It might be OK when it is cold.

AC Wing.

Good post, I gave you a GA for it, my thoughts entirely.

BTW the WD40 ideas was recommended by someone else's post only as a quick test, not as a permanent fix.

For such a test, WD40 is perfect and often easier to get into a difficult area than an oil can for example....I have used it in similar situations myself, it helps diagnosis.

Hi Mr Wing, I gave you a good answer point for a really good post, also your English is better than some of the UK and US born people!!! I include myself on this too!!!

Really a good idea about the shorted turn becoming un-shorted for some reason......I won't forget that!!!

Joke:-

Is your Brother Mister DC Wing?

Hi Andy,

Thanks! I might have a lot of brothers in the AC family! The DC family probably are distant relatives!

By the way, I agree WD40 might help, actually I used it with my fan at home, but I took it as luck only.

Hi Steve S,

I also want to know your find out!

Cheers,

AC Wing.

Thanks AC! BTW I did try turning it by hand (with the power off) and it did not seem to have any sticky spot and turned freely, but it did not seem to turn as freely as I would expect. Usually when set spinning it takes a few seconds to coast down. This one coasted down much faster.

WOW,

Every body hold the Press or horses. It is just a 1/4 HP fan motor, replace it, then take it to the PUB and Drown it.

It runs, is the voltage low causing high amps and over heating, thus swelling the bearings since they are brass or bronze. Is the capacitor leaking and over heating then causing higher amperage on the motor, resulting in overrheating and bearing seizure.

Remember each time the motor or bearings over heat, the viscosity of the oil breaks down causing schelaking of the bearings and eventual failure.

Bottom line spend the money and get rid of the motor with a new one.

What if the bearing's got no lubricant in it?

What'll dropout of it then?

I think you're right, just take it to the bloody Pub and try to sale it to the boys for a pint of beer and let them pay for a round of pool game to give you the chance to finish up your beer peacefully.

Try to let them also know how lucky they should feel to have it for as little as that and let them win the game.

cheers,

capasitor shortage, short winding cause motor overheated, does not cause bearing failure yet. I have replaced so many condenser fan motors.

Motor thermal protection becomes open circuit when overheated, no current flow, motor quits, as simple as that.

When it cool off thermal protection engage again, current flows, cycle repeats.

Change capasitor and motor together.

Armanto

Louisiana

It is MOST unlikely that this is a capacitor start or run induction motor, probably less than 1% probability.......so a 99:1 chance or thereabouts!!

Most of these fans are a much simpler design with a shorted turn, shaded pole, but NO caps....

It's time to change the bush/ bearing of the fan

Well due to work priorities I have done nothing with it other than to turn it off. Fortunately the Houston area has been unseasonably cool this week.

Friday I'll go take this apart and I promise to post pictures....

Back in the late 1940s, my parents had a similar problem with the fan motor for their chest freezer. No replacement parts, very small budget and a friendly service man helped with the motor life extension project.

Dad drilled a small hole through the case from the top to each porous sleeve bearing. Thereafter for about 10 years, as I recall, he added a couple of drops of oil through these holes whenever the fan slowed down. Neat life extension, I thought with all the clarity of the middle school student I then was.

HAVE FUN

BTW, 2 reference cases for your perusal:

1.my fan at home had the same trouble and WD40 helped, it is still working after a year of adding WD40. I actually was preparing to dump the unit, therefore did not mind to give it a try.

2. I know a manufacturer used car engine lubricant, Mxbxx 1, very good one on these kind of sleeve bearing and they had a lot of rejects a month or 2 after delivery! Some of the motors were actually jammed! Lubricant actually clogged up!

My understanding is the newly added lubricant must be compatible with the original lubricant and the spacing of the porous bearing.

Hope that help as well.

Cheers,

AC Wing.

I have occasionally drilled a small (1/16") hole in the inaccessible brush end of an automobile blower motor. A shot of WD40 or Blaster will usually turn a frozen or noisy blower into a quiet one till a replacement can be procured.

Steve. Have you tried an amp reading on the blower motor and watched as it slowly died? If the bearings are the problem the current should go up . If it is a connection the current should drop. (I think) (only occasionally). Good luck.

I brought my multimeter with me, but did not poke around much. I pretty well figured it was the motor.

I did notice a bunch of old bus fuses in the circuit. Any possiblity one of those is acting up?

Behavior problems with bus fuses are rare. The threat of electrocution usually keeps them in line.

Bus fuses not, but the holders can be bad.....I had a bunch on an important machine that were only riveted, after a year of different temperatures, the rivet was loose!!!!

but I do not really think that is the problem, worth checking though.

My money is on a bearing!!

You are absolutely right. Years back I had a building with an aluminum meter box. One of the rivets on one leg of the contacts became loose. We could not see it under the meter. One leg of the house would go dead. Shake the meter and the connection would join again again. Electric company came out , put in a new meter and did not see the marks. After a month of finger pointing and blame passing, the electric company finally replaced it. My last reply was only because I thought it was my turn to be a fool.

Hey guys don,t forget this is a AC fan motor that draws its power from the same wire that the compressor does and I have seen a faulty or bad compressor drawing the amps to start up causing fan to slow down !!!!

and as for wd-40 it is way to thin and has bad things in it that eat the bronze brg a light machine oil of 5-10 wt shod be used not a penetrating lube like wd 40 if brgs are the fault clean with a electrical contact cleaner or mineral spirits and re lube with oil not penetrating fluid use the rite tool for the rite job results much better finished product BTH if no oil ports allow oil to run down in back of vents or any opening that will allow it to drip on brg as stated above most have a wick type oil retainer and after cleaning and a few drops of oil turn and re oil turn and re oil should fix for a year or so if you have a lot of play in brg's replace motor

No, this is the blower in the air handling unit in the attic, not outside with the compressor.

Steve, the blower for ac in my attic is a two phase motor with a capacitor. When it was the capacitor problem, it took a loooong time for the fan to spin at the rated speed (by the way, it has two speeds, changed by the almost elementary logic). Than it was sluggish, so I replaced it. It was some $80 (amazing, but that was the price - 3/4 hp, I guess). On the other hand, the fans in the ceiling are working "non stop" starting March and ending November. Not any problem in the last 22 years.

I am interested in why you say a 2 phase, is it because its connected phase to phase in the USA? eg. 220volts instead of 110volts?

Slip of tongue (hand). Domestic "two phase" in USA (at least in my part of the USA) is derived as 240V with a central tape. The central tape is connected to a good grounding rod. So the motor is connected like to two phases (not 120° but "only" 180°). When I have replaced the motor I just matched the color of wires. A guy who is knowledgeable in motors could explain what phase change results from the capacitor.

End result is that its in reality a single phase motor, or would be if the same motor was connected in Europe between line (phase) and neutral at 230volts.....

You have to be an American, speed reading without understanding again :-

1) How do you know that in the machine that there are NOT 2 fuses, one for the main compressor and one for the fan? (That would be a good design!) Have you been sent your own personal copy of the schematics so you know there is only one fuse????? Also, this is NOT thought to be the problem either, if you had read more carefully.......!!!

2) The WD 40 is just to short term TEST as to whether lubrication is the problem NOBODY wants to use it as a permanent fix, though some have had good experience in this area. This is the THIRD time that has been written so clearly. Please try to read AND understand the details at the same time, it would really help us all here.....you are not alone, 100 million other US citizens read too quick to understand too!!!!

Is your middle name Homer too?????? DUUUUUHHHH!!!!

You have UN-impressed me to a great degree in one simple post!!!!!!!! I am sure that I am not alone either!!!!!

READ SLOWLY, if you cannot remember for long, write it down somewhere or print a copy of the post you want to reply to!!!!! ITS THAT SIMPLE!!!

Gee Andy Or is that GRUMPY in America we use circuit breakers not fuses and as stated wd 40 is a water repellant and yes it does have some lubricating properties inherent to petroleum base it also has graphite and other things that contaminate porous metal and can plug them up so that the rite lube can no longer work as designed.

with that said I would wonder what it is that you have designed using the wrong thing to something it is not designed to do?

Don't believe everything you read or all Germans so gullible?

Just because of some fancy advertising and luck

and as to fan no mention was made to evaporator or condenser

but ether way best bet amp out load read and compare to nameplate on side of motor then replace it as most likely as you said Steve it was sealed so not much to do with it just like a BIC lighter great wen full throw out and buy a new one when it dead

If you had read all of this blog carefully, you would have understood fully that the intention was by several people just to free the motor using WD 40, to see if it was the motor bearings that were causing the problems seen and if the answer was yes, the motor ran better, then replace the motor.......it is only a cheapy.....

But just replacing the motor by guesswork and then finding that the control was the problem and now the new motor is possibly damaged, is not quite such a good idea.......

Engineers always want to KNOW exactly and the time and cost are minimal for such a test!!!!

Nobody was trying to make a long term repair with WD 40 as so many of you misunderstood (you are certainly not alone if that makes you feel better!)........it was a testing tool only to try and solidify the problem into fact not fiction. Nothing more, nothing less.....

I have been a user of WD 40 ever since we used it in the RN to wash down helicopters. (Magnesium and salt water are not a good mix!) and found that it had many more uses than just getting rid of salt!!

With regard to advertising claims, I have been using it for so many years, that I believe that I know its good and bad sides quite well.

There is a WD 40 FanClub that is well worth a visit if you are interested in some of its less well publicized uses....

A good engineer understands the limits of ANY tool that he uses........and uses it WITHIN those limits......most of the time at least!.......except when he is trying something new!!! Like reviving a cheap motor for a specific short term test!!

You are absolutely right - If the compressor was over drawing current it would slow the motor, but it would also brown out about everything in the house, as most compressors are 220 here in the US and effect both phases in the home. We all have seen the lights dim when a good compressor starts. If the compressor was drawing that much all the lights would dimm and stay dimmed while it was trying to start until the overload kicks it out or the breaker goes.

As far as the lube info - I am an electronic engineer not a lube engineer, so I can't say? I was always told that WD-40 was a light machine oil heavily thinned with acetone so it would flow deeply in (Penetrate) and then the acetone would evaporate leaving the oil to do its job. Sometimes old heated grease will get hard and stiff, the acetone would help desolve the grease and the oild would mix into it and some what restore its original properties. It also helps to flush out any dirt or metal particles too.

I was not aware that it damaged bronze bearings? good thing to be aware of and look into.

Re: Side line of WD40 as a lubricant... or should I say lubri-CAN'T.

WD40 stands for "Water Displacement, 40th try" because the inventors were trying to come up with a DEGREASER and rust inhibitor. I capitalized the word degreaser because if you think about it, that is the OPPOSITE of a lubricant.

It has some mild TEMPORARY lubricant properties, but in actuality it does a worse job of lubricating than whatever was there in the first place. IF you have gummed up grease or oil which is robbing you of shaft power, then spraying WD40 will clean away the dirt in the lubricant, but does so along with the lubricant. So sure, it is a good way to see if that was the problem, but DO NOT leave that as your only lubricant; replace it with the proper stuff.

What you say is patently NOT true, you have obviously little or no experience of the product.

From the web site, read the following:-

Known as "the can with thousands of uses,"

WD-40_® protects metal from rust and corrosion, penetrates stuck parts, displaces moisture, and lubricates just about anything. WD-40 is also great when it comes to cleaning grease, grime, and other marks from most surfaces.

I have underlined the word that you should pay most attention to........!!!

Click on this link to learn more about WD 40:-

wd40

I have used it many, many times and it is a lubricant too, but for many parts not a long term one.......it allows something to be freed up and then to be lubricated with the correct substances......

The only way you can be sure if you are using the right lubricant is to contact the manufacturer, ask them for what they are using. They most likely would keep you out of their door because that might be thing they treat as commercial secret.

Even if they let you know what they are using, their supplier would definitely not let you know their formula and most of them would only do business in bulk order, which many consumers would not do!

As I said before, the right stuff to use must be stuff that match with your original stuff, or it would even clogged up inside the bearing. I am almost hundred percent sure that if you go to these lubricant supplier and ask for stuff that can replace theirs, they would jut tell you theirs is the only right stuff to use!

Lots of hassle in finding out the right stuff are anticipated. WD40 has never been the best choice, it is however better than using wrong stuff, and it at least gives you the direction to try and would not clog your bearing with the shaft!

There is an American company called Permawick (try www.permawick.com), they produce the right stuff for these kind of bearing, but they might not sell you small amount and even if they do, do their stuff match with what is already inside the bearing? Nobody knows. Many manufacturer might not even know what is the right oil to use!

AC Wing.

Who really cares about whether the new lubricant is compatible or not? It (WD 40 for example) should only be used to see if the fan runs longer or not.

Once it has been proved to be the motor itself, throw it out and put a good quality replacement in its place!!!

Total cost probably $8 or so for the new fan??? maybe even less.....its simply not worth the trouble of further thinking.....

I always value parts against my own hourly rates and that one is a "no Brainer".....chuck it!!

Are you certain th fan is slowing? or is the air flow dropping off due to the evaporator coil icing up?

Yes I watched it slow down, and there is no ice on the evaporator.

Lots of good responses listed. The fact that it is a 1/4 hp motor it will be a cheap sleeve bearing motor. Lubricated for life is the term. Life may be over. The question I have, is the blower assembly belt drive? HVAC blowers along with low horse power motors tend to use sleeve (sintered bronze pre-lubricated) bearings. If it is a belt drive system than it may be a blower-fan bearing problem and or a combination of both motor and blower. Try running the motor alone with out the belt (AC off) and check the blower separate. It should turn for several rotations after hand spinning. Either way a 1/3 HP motor is usually considered the minimum for AC applications due to the density of the cool air.

May not be a problem, it may be a power and sound reduction feature of the unit, the motor speed is controlled buy the control system and it may have determined that it could reduce the motor speed.

I have that feature built into my units (X2) and I frequently notice their speed changes as you describe. My units are about 8 years old so this feature has been available for that time period at least.

Several of my computers also have this feature, My large HP Server comes on like a fleet of Vacuume Cleaners and then quickly slows down the fans once the internal temp is withing parametes. On hot summer days, it breiifly speeds up again for short periods to bring the tempature down.

Hope this Helps

Yeah, that could be the problem, if it was a fairly new unit. This gear is the original equipment that came with the house 28 years ago. Not nearly that sophisticated.

Hire yourself a "Fan Boy." Good for you, and gets some poor kid off the streets!

What about a "Fan Girl"? Far more attractive and more likely to raise the temperature!!

But each to his own of course.......!!

I would not write that off yet, it is a very common feature, I spoke to my AC man who is a 2nd Generation AC man, he as 38 years in the business and he said that this is a common feature. He said that the induction motors are generally 2 speed motors and a simple themostat controlled relay selects the voltage.

If it is a two speed motor it will have 4 wires - Ground, Neutral and 1 for each speed.

If there was a problem with the motor and bearings or some outside force was causing it to slow down then the motor would get hot and get hot fast, induction motors slowed or stopped quickly become induction heaters.

If touching the motor when it has been running slow for a few minutes does not cause immediate motivation and scarring, then you may not have a problem.

Most of the time it is hot and the fan runs at high speed but when it is more moderate the slower speed is plenty adiquate to cool the coils. Other wise the compressor would be switching on and off to compensate during borderline periods and this would cause damage to the compressor. Many compressors have more than 1 speed too, 1 of mine has 2 speeds and the other has 3 speeds for the compressor, I have seen a large commercial unit with a 5 speed compressor. This is to maintain a more comfortable environment.

Early in the AC days, it was determined that during the moderate temperature periods, AC units would cycle on and off frequently and would be both bothersome and also very damaging to the compressor, shortening its life cycle.

It is much better to run the compressor and fans slower and do speed changes as opposed to full start and stops.

Newer systems may use electronic peak suppressing or wave compensation to control the speed of both the compressors and/or the fans individually and a microprocessor that analyzes and can adjust the speed to any speed determined to be optimal. These motors are standard 3 wire motors.

For 20 + years there have been AC units regularly installed with 2 speed fans and or compressors. It takes very easy to check, how many wires are running to the motor.

3 Wires and it gets hot - Replace the Motor and forget it, 4 wires and can touch motor without jerking fingers to your mouth, go back inside and enjoy the comfort.

There are very few external things that can affect the fan speed, if the wire used to connect the whole system was inadiquate, the cycling of the compressor could cause it to brown out, a voltage check would detect that and every other possible external problem.

If it was a large commercial unit running on 3 Phase power, you might have a bad leg that is fluxuating, but never seen a 3 phase power system in a home.

If the Motor is not hot, really hot, then you probably have no problem. Low voltage (Brown Out), Dropped Legs, inadiquate wiring, bad bearings, rubbing fans, tarred lubricants, and just about anything else that would slow the motor would also result in the motor heating up and quickly. An induction motor will get hot if it is not running at the proper speed due to the edy currents generated.

If you can not see the wires, measure the voltage etc. - simply check the motor temperature and if it is hot, replace it.

Isn't it a CE requirement that thermal fuse connecting to coil must cut all current off once the coil temperature exceed the speicified temperature? Once current cut, temperature would not continue to rise. It would eventually drop to let the thermal fust to reset.

I still think it is a sleeve bearing trouble, according to what Mr. S said.

AC Wing.

Hello Steve S,

More than likely the bearings are babot style, meaning they have a finite life in which imbedded oil in the brass will self lubricate. Your bearings have all but used up their oil. Replace the bearings or replace the motor if they are not replaceable... Spec it for ball bearings with a lube port on each end bell of the motor. Match the motor for horse power, service factor. (sf) and rotation: That data is in code form on the name plate but is decipherable if you use some brain power (can't be too tough if dumb ass service mechs can figure it out). Lubricateable bearings need a couple drops per year - don't forget... otherwise the motor will straight out seize and you won't get a few days/weeks more life out of the motor once they go dry. The benefit of ball bearing as opposed to babot bearings is length of service life and slightly less energy to accomplish the same load.

Signed: Retired Air Conditioning Service Contractor

Or he could just hire a Fan-Boy for a lot less effort and money! Hello!!!

2 quality ball bearings at both ends of the motor cost even more than the shaded pole motor itself, let alone to say the housing for the bearing need modifications, hence money!

AC Wing.

Dead right Sir!!!

check the condenser/capacitor in series with the motor( used to adjust the power factor). it must be heating up and leaking current hence the problem. replacing it will sort the problem.

Regards,

S D Lashkari

The motor in question is almost certainly a shaded pole motor. No capacitor.....!

they are also the ones with cheap sintered bronze bearings that lose their oil over a relatively short time too.....!

Here is a picture, you can see quite clearly the thick copper wire shorted turn that allows the motor to start and run with no starting cap in circuit......they are exceedingly commonplace and very cheap!!

Well done Andy.

I don't think some people bother to read the previous comments by others before they make a reply.

It's been said so many times that there's no cap in it already.

I have been guilty of it myself and also (correctly!) been told off for it, but this blog is extreme in this area.....

I put it down mainly to the USA, where over the last 40 years, "speed reading" has been advertised, books sold etc etc., and people believe that it is a marvelous ability. It is, but the biggest problem is that none of the people concerned have actually learned to "FULLY READ" the article at speed. They just gloss over it.......

It would not be so bad if they could accept it and improve themselves, no, they get pissed off!!!! Morons!!

I speed read too, so I also need to be careful as well!!!

Sadly, I also "speed write" and make many spelling mistakes that I mostly fix with the spell checker!!!!

These motors have not Capasitors, Capacitors are to start the motor, not to adjust power factor, once a motor is running the Capacitor is removed from the circiut on cap start motors usually by a centrifical switch.

A capacito resists a change in voltage and an inductor resists a change in current, this causes a delay in effect creating a second phase that acts against the main phase giving the apposing magnetic field required to start the motor turning, once it starts to spin the centrifical switch removes it from the circuit.

Once the Motor is spinning, you can remove the Capacitor completely and will not affect the motors running. If the centrifical switch does not remove it from the circuit, the motor will become a loud buzzer bent on self destruction.

Since these motors dont have one, no help. But the Compresors generally do.

Cap-start motors are generally used when the motor will need to start under load such as the Compressor, It will generally have a Start Cap.

Simply the Cap is used to generate a temporary aposing magnetic field that will start it turning, then the normal coils take over from there.

If the Motor is running and then has a problem, not going to be the Cap. If it is a Cap motor and won't start, it may be the Cap.

You wrote:-

Simply the Cap is used to generate a temporary aposing magnetic field that will start it turning, then the normal coils take over from there.

That is technically rubbish......! Sorry. Your spelling is also awful..... Why not use the spell checker? Its so easy.

Please look at the following link for a simple CORRECT explanation:-

http://en.wikipedia.org/wiki/AC_motor#Single-phase_AC_induction_motors

Ge I am only a design engineer with 38 years experience and i guess I was lernt all wrong, my qick drop to techy level explanashun failed to meet you obvious vast nowlge of the univers expectations, lets hear your explanashun of how it wurks - I could use a good laff

You obviously are a Snob and not a very smart one at that. My statements, elementary as they may be, are correct, it is your technical knowledge that is lacking and you do not even have the backbone to respond. I asked for your understanding of how it works and you gave your answer - you have no idea.

It is my typing and eye site not my spelling, frankly, I did not notice the spell checker, or I would have used it.

I wish I could buy you for what your worth and sell you for what you think you are worth too!

If you feel you can just insult someone and blow them off then you are low life and not worth any more of my time.

Woof!!! Does the term "Don't take it personal" mean anything?

Check this out instead...

Easy to say when your nuts aren't the ones being kicked.

Where were you with the "Don't make it personal" - that is the proper quote.

I came in friendly and trying to help, I didn't start it, but I am not going to let some pea brain take a swing at me and walk away.

But I do think you are right, that is a much better subject. A GA in my book

I tried to get in before Andy but I missed. You could not be more confused. And certainly you have never touched equipment like this. Try looking up what a "run" capacitor does in a motor system. After you have read it SLOWLY I suggest that you clearly state some thing to redeem your self.

About speed reading Andy...As much as it pains me to agree with someone from the "old country" your are correct but not for the reasons you state. You are correct because here in the colonies we (men) feel like we know whats coming ahead in all conversations. We are wrong of course and our wives remind use daily.

I do agree with you that in too many threads people jump in and give non answers very quickly without understanding the question.

Nice and funny post, many thanks.

I could use a good laff from you too - go a head and give me your full understanding of the operations of the capacitor and its relationship in the LC circuit, magnetic field theory and its function during start and run. Don't quote it out of a book, dump it from your vast knowledge of the Universe right out of you head bioler boy

If you choose to joust please consider "laugh" and "boiler" as better less embarrassing weapons.

Ok, the moment you have all been waiting for. First of all a recap because a lot of you are confused. This is the fan motor in the air handling unit in the attic. It drives a squirrel cage fan overhung on the motor shaft. Not in the compressor unit outside.

New motor and a new cap cost me $174 USD. If I had a service guy do it, probably would have been that again in labor. I might have fixed this motor, and I may still to keep as a spare, but Mrs. S and all three of my S. daughters made it very clear to me this morning that the house was too hot and I needed to do something about it. The S. sons were fine... At any rate the $174 was worth it to make sure the women have cool air...

First thing to note is that there is indeed a capacitor in the circuit. When I replaced the motor, I replaced the cap as well just on principal.

That is the cap there in the upper right hand part of the picture....

When I got the motor out it was very difficult to turn by hand, obviously bearings..

That looks to be a single phase induction motor with either capacitor start or capacitor start and run.

That type of capacitor can often become defective, so changing it as well was a good idea.

On this type of motor, you can usually clean it up and replace the bearings (carefully) for very little money and then you have it as a good spare!!

The price was not too bad for new motor and cap.....

It makes me laugh to agree again but you are correct Andy. Knocking bearings out and replacing them should be done gently. If you look at the fan wheel you can see why the bearing went out the fan looks filthy. I hope MS.S told Steve to clean the fan while he was spending his $174. Steve time on this thread should be worth a lot more then that but as stated earlier each to his own.I a more civilized area of the colonies that fan would be pulled out annual and cleaned reducing the MTBF.

Good post, I gave you a GA too....

I a more civilized area of the colonies that fan would be pulled out annual and cleaned reducing the MTBF.

Definitely Houston, Alief area, is not one of those more civilized ones. The fact that the temperature reaches 120° is not an excuse. Nor that the attic is, in fact, a crawl zone. When I replaced the blower motor (the one with four wires and capacitor) it was winter, only 70° (well, one day), and I did as in my short military training: from lay-down position digging my individual hole with the infantry "little shovel" in one hand, the mask on (with the removed valve - ha, ha), and the 1915 carabine in the other hand..

Yeah, what Indel said!! Mike....

I think it is wonderful that Texans still defend each other. I also don't care about that fact that you are to cheap to pay a 19 year old rookie AC tech to crawl around your house. I do applaud your tenacity.

I wish you Texans would have had more back up at the Alamo though.

I also don't care about that fact that you are to cheap to pay a 19 year old rookie AC tech to crawl around your house. I do applaud your tenacity.

Yeah, I tried to tell my wife about all these (except Alamo - she wouldn't take it, she is Chinese), hoping that I am safe from crawling. But she, with an ingenue air, asked me: and what of electro is that degree of yours?

For the wife I say: thanks for the interest, and 17 years in the aviation industry, the last 20 in the HVAC industry. 3 minor electro's in manufacturing, production planning and management.

It only took 37 years to get the "fix anything that spins, pulses, sprays, burns fuel, grinds, sustains flight, uses electricity, solve problems and try to be patience when people ask dumb questions" degree thanks to a lot of genuinely brilliant people like your self that I have had the good fortune to meet along the way. I am glad your home is comfortable now.

I hope that you will allow me to show your posting to my parole officer, 'cause he thinks something different about me.

Thank ya, Governor.

wow with all that knowledge then perhaps you could pul this out of your noodle.

In a SPV Terminal unit has a 6" unit size with the Air Flow of 143 L/s 300 cfm and a 250PA (1.0" W.G.) what would be a good Sound Power Level, Lw dB, RE 10^-12 Watts for the 6th Octave band? Any one claiming that much engineering background cold give me a reasonable answer off the top of their head. Points will be awarded if you can give me answer within 50% of good.

Other wise quit blowing your horn as it is getting hard to tell which end the toots are coming from.

It only took 37 years to get the "fix anything that spins, pulses, sprays, burns fuel, grinds, sustains flight, uses electricity, solve problems and try to be patience when people ask dumb questions degree" I forgot to include the on going course directed at developing tolerance for people like you.

I am certain in real world hands on problems solving I could stand next to you but regarding this sticks and stones kind of crap I give up............You unfriendly knuckle head.

By the way where did you "Engineering Degree" in my thread?

It was you that started the attack on me and obviously you are the one that needs to read up on the Capacitor and its use in a motor circuit. The Capacitor in question is not a "Run" Capacitor , it is a Start Capacitor. The start capacitor is used to provide the initial torque to start the motor and this is done thru exactly the method I described and you attacked with your petty insults. A run capacitor is used to make the motor run more efficiently. The run capacitor if removed will cause the motor to run less efficiently, but would not cause the motor to slow unless it was shorting out and then very quickly would let you know in its own way. The start capacitor is removed from the circuit once the motor is running and that is the capacitor in the picture obviously. So it to would not cause the motor to slow if it was bad. If it was bad the motor would have problems starting or not start at all.

You very well may be good at fixing most everything, so am I, we both have had a lot of field experience. I am a Certified Engineer (3 certifications to be exact) and I have a lot of experience in HVAC design and engineering for the commercial HVAC industry. I also an Electrical and Electronic Engineer with a complete understanding of Capacitors and Capacitive Reactance. What I stated about the operation of a Start capacitor was less than complete, it was accurate. But since this information is not required to service this equipment a more general description is to be found in the equipment manuals. Below is a typical description of the terms generally given which I pulled from a major HVAC site:

"There are two basic types of motor capacitors most commonly used in HVAC applications today. The run capacitor and the start capacitor. Motor capacitors are used to either increase run efficiency of the motor or to give it an initial start boost in torque to a motor. They are sometimes referred to as motor starter capacitors or power capacitors."

A field tech has no need to understand the electronic theory behind every part of a circuit only what is needed to diagnose and correct the problems, basically returning the equipment to the engineering specs. As an engineer I do have to know and understand every part and its exact operation. Having designed a lot of equipment for one of the top three HVAC companies in the world, you may very well have worked on some of my designed equipment. I to have an Avionics background from my Air Force days, probably not to your level. I am a hands on engineer and have traveled most of my life to resolve issues that no one else could. In my 38 years as an engineer, I have had either full are partial responsibility for 1,415 patents and well over 20,000 copyrights. I have designed Sonar and Weapon Systems for the Navy, Computers for IBM, and HVAC systems too.

I know exactly, 100% how the capacitors work, their purpose, why they work, how to size them for every need and even how to make one. I am not some geek who sits in an office somewhere with a pocket protector, I get down and dirty with the techs all the time because I am an hands-on type. I clean the grime from my finger nails with a pair of wire cutters and have very few articles of clothing not stained or otherwise damaged from working the trenches. I am damn good at what I do because of the time I spend in the field and I have learned a great deal from people like you who deal with it every day because I listen to them when I work with them. I have a great deal of respect for those who work in the field and I am sure had we met in the field we would get along great and we could both learn a lot from each other. I have personally replaced well over 1000 such motors and up to about 100 HP units, not an few observations of someone else doing the work. I have gone home so dirty my tea shirts were black thru my shirt. And I do know how to calculate the Sound Power in that simple example I posed too because I have done that more times than I could count.

Maybe there were a few errors in my writing as to spelling, mostly bad typing, poor eyesight and severe multi-tasking. I considered this forum to be informal and friendly and did not think it was a big deal and frankly IDGAF because I was not trying to impress, only help.

I am certain in a real world hands on problem solving, we could stand next to each other and hold our own and we would probably both come away with a lot of respect for each others skill.

I am a very friendly person and I may be a lot of less than desirable things, but a knuckle head isn't one of them.

Perhaps you should have been a bit more careful of your words when you started throwing the sticks and stones in my direction. Where I come from, we don't start something and then back away a put it off on the one we started it with. You insulted me and don't really know what you are talking about because you are not trained as an engineer "in your thread". You could have diagnosed and repaired this in your sleep I am quite sure as could have I.

I read a lot of responses I thought were less than Brilliant the difference is I did not attack them and imply they were stupid. If I did, I would have either stood by my words or admit I was in error and apologize, not some lame sticks and stones line with additional insults. Your response was without a backbone and a poor additional collection of kiddies insults. If you were half the man you think you are you would never have made those insults. You attacked me and then called me unfriendly for responding - your response was chicken S---. You further feel you can brush this off on me to the forum with additional snobbery and insults. You don't have a hair on your butt.

I have a lot of hard learned training, nobody paid my way, I worked a full time job all the time I went to school to learn all I have and I paid every penny out of my pocket. I worked hard all my life as I do now. The difference is I don't look down on people who know less than I might, I have a respect for people.

I respect you because you have worked hard to get the knowledge and skill you have and I am sure you know things I do not and I am sure I know things you do not. If you have to build a "tolerance for people" then you damn well think you are better than everyone else and your arm must be sore from patting yourself on the back. I got news for you, you are no better and probably worse if you feel you are so superior. I wish I could buy you for what you are worth and sell you for what you think you are worth, I could retire much happier. What you have exhibited has been crude and rude and socially unacceptable. Most of the people on this site are tolerant of you, just polite enough to not state it. Being good at what one may do is no excuse for one openly being such a snob, you are not that good by a long shot.

At any rate you are probably pretty good at what you do too. I can respect that and I am sure that this whole thing is nothing more that a poor choice on both of our parts. Had we met on the job we would probably be having a cold one after a job well done and trying to impress each other with our past stories. I hold no ill will and should we meet the first round is on me. So your an AH, so am I, so what, drink up.

The answer is 4' 2"!!!

Who did u need the 1915 Carabine to protect yourself from, your wife?

If she's that type then that thing would not have given you enough protection from her anyway.

He needs the carbine to fight off the possums and racoons that often live in attics in the Houston area. Big nasty possums with really sharp teeth. One either needs a M1, or a holy hand grenade...

Crikey I didn't realise it was such a huge fan. Main thing is - it was the bearing after all. It could have been the cap too but the descriptions you mentioned before did suggest that it was the (front?) bearing since it was getting too warm.

Naturally, I too would replace the bearings and the Cap to have it as a good spare.

Sounds like you must have a good weather there if you need to run it this time of the year already.

1/3 Hp motor......

This motor is buried in the fan housing, and you have to pull the fan housing to get it out to be cleaned..... The motor has been in service about 10 years so I am not ashamed of the MTBF for this component.

So I am not feeling a bit guilty about my lack of PM. So there Mike!!! Thwipht!!!

Mr. S,

It is a really big motor. The bearing is the root cause. Instead of using the shaded pole motor we suggested previously, material-wise, the guy used this kind of induction motor was really trying to do a good job, although it is a hard to service design (I might be wrong, got this impression though). BTW, this is the kind of motor used in many dishwashers.

I also agree changing the bearing as well as the capacitor is advisable!

10 years is just the average life of this kind of bearing. SKF said theirs are better and would last longer (no actual data from me, they probably have theirs), NTN are also not bad! Judging from the age, it is not that filthy I reckon.

BTW, ball bearing like this must be handled with care! Don't drop it, it is like eggs! You can only press the outer ring (don't know if it is the proper name) of the bearing when you assemble it onto the motor house, when assembling it onto the motor shaft, press the inner ring only; or you would damage it (deforming the bearing, shortening its life)!

Good pictures, good luck and thanks.

Cheers,

AC Wing.

I think it is funny that you guys consider this a "really big motor." In my work I deal with 10,000 HP induction motors and 20,000 HP synchronous motors for compressor drives. In my business I would consider a 100 HP motor to be pretty small, so a 1/3 Hp motor to me is tiny...