AC Breaker Trip

GEEEeeeh... Probably capacitors problem there. Sometimes a little delay time breaker (mili ) that hold on just a little until that puppy stabilize to stay on line. I don't know but also will be good to do a unit check for operating pressures and all of that stuff, you know like a PM maintenance proccedures to be sure that Baby is up-date. Will be nice to check up for terminals and wiring connectors inside unit all over just in case, you know the deal. Also probably by installing a -Kicking Kit- device that help out with some starting issues will be a good idea as well. Also nice to re-check compressor windings (Ohms). Lock and Tag for safety measure just in case.

Capacitor Torque,

MC

At initial motor starting current will be 5 times the full load current ...so it is better to use some motor protective breaker instead of normal mcbs

There many possibilities.

It sounds like a breakdown in insulation on the wires. This could be anywhere from the circuit panel to the compressor motor itself.

Most intermittent faults can be traced to movements, vibrations, or temperature changes. I would check the compressor end first since that is where the most movement and temperature fluctuations are. It could be caused by a improper stress relief in the connection box at the compressor.

The compressor wiring could be damaged, or have water intrusion.

The compressor bearings could be damaged. (it would also be more noisy)

Good advice to call the AC expert.

Costs depend on the problem

Cheapest end may simply to repair the wiring connection = Labour $50-100

Most expensive (and most probable) - you may have to replace the compressor or the whole AC Unit - couple hundred to a couple of thousand dollars.

Check the A/C nameplate. It should show the MAX "OC Device (max breaker size).

That 20 might be a tad to small.

GA

maybe you need a slow fuse type?

hi

most likey the compress has a internal short circuit inthe coil .. also could be the capacitor used to start has become weak ... There also could be a blockage inthe gas pipes... the only thing to check easily is the capacitor or short between thelbody of the compress and line

hope this helps

Reminds me of earlier sealed unit start-up probs- the sealed unit has start -run windings- the start winding is energised by a solenoid for several seconds at higher amps, then run windings take over at lower amps, the start windings being disconnected- but if solenoid faulty & START stays connected, the higher amps causes protection to activate to shut unit down. Later units have screw type compressors, where start up fault is usually start-up capacitor s/c- these caps are 440v ac- testing is by applying ac 240vac via a relevant wattage light bulb in series- a faulty cap will keep the bulb bright- ie cap not charging.

GA. I had forgotten about short cycling.

Yea but you came to the more sensible approach to a little unit. Replace it with a new, more efficient unit for little more than whats going to be spent for this man to hire an A/C technician to patch up his old unit.

Sometimes its just best to cut your losses and move on to more important problems. Unless the unit has some sentimental value.

I have seen on oil rigs where men would spend countless hours repairing stuff like washing machines!!!!???? In my mind, the money they wasted in labor that would have better been spent on real production equipment out weighed a new machine at least 10 fold.

I try to not let logic and common sense interfere with a good plan.

The unit could be overcharged with freon.This would cause "slugging" of the compressor under light heat load,because liquid freon will enter the compressor on the suction side,causing overload,and could ultimately cause compressor failure.Check the superheat,it should be around 10 degrees to provide a safety margin for the compressor. Subcooling should also be checked.Proper subcooling ensures that only liquid is present at the expansion valve.If you are not familiar with these terms,have a qualified A/C man do it.Slugging can also occur ,as previously mentioned, if the unit is short-cycled.Also make sure you are using a HACR-rated circuit breaker, which is designed for the current surge typical in an air conditioner system.Standard breakers do not perform well on air conditioners.

The previous advice regarding wiring and capacitors is also legit.

Hope this helps.

HTRN

HTRN,

If the A\C unit is still sealed with no service ports installed, is it possible to be overcharged?

camranhbou take note of this answer. I believe that your A\C unit was sealed with no service ports.

Where does he say no service ports?

Most units come from the factory with service ports, with the exception of some refrigerators and freezers.

The evaporator coil could be dirty, preventing the freon from fully flashing to a gas,and this could cause "slugging" of the compressor, a result similar to overcharging,but my bet is,since the unit is very old, it has probably been serviced in the past, and an ad-hoc A/C guy did the work.

By the way: are you an A/C qualified (EPA certified) mechanic, or are you still studying for the exam?

Could be an I D Ten TEE error,no?

He did not say "no service ports". It was I that felt that an A|C unit that has been working with a 20 amp circuit breaker, was not a large unit. I felt that most units in this size range are sold as sealed units. That is why I questioned the high charge answer. Thank you for resolving that issue.

My A\C certifications are from ASE, EVT and IMACA, which predated the EPA certs. How nice of you to inquire.

Have you been issued a name yet, or are you still studying for the exam?

I am still studying for my name.

When are you going to bring your certs up-to-date for residential,commercial A/C units.Vehicles use the same technology,but there are differences.In the US an automotive certified A/C tech cannot buy Freon in large containers for residential, and vise-versa.

A service port can easily be added by any tech, and I presume the unit was not malfunctioning when new, so something has changed about the system..Dirty, or another variable:(freon).

My line of work is almost all vehicle related. There are some RV type units installed in the trailer units, but the similarities to automotive are enough to allow me to keep them working.

"I presume the unit was not malfunctioning when new, so something has changed about the system.." This is very close to one of my favorite diagnostic questions. " What has changed since it was working correctly?"

Remember, sometimes you need to either accept these type of people or forget em.

Wow heres an idea, why not install a real nice new dryer in the system while the service ports are being incorporated into the little unit...How about some permanent pressure gauges and an amp meter while your at it.

Define "these type of people"

The are just like most people, except that they all look exactly alike, sound exactly alike, and have no distinguishing features. Sort of like a colony of ants. You really think that there must be some distinguishing features, but if they don't care, why should I.

Kida like democrats.

"Kida like democrats" politicians

While you are at it, install a receiver, an accumulator, a new expansion valve, a new compressor,evaporator,condensor,isolation valves, digital thermostat with PID control of room temperature,with RS485 interface to your PC so you can control it from the internet from anywhere in the world, solid state pressure transmitters with alarm setpoints, RTD temperature sensors on the compressor windings, a telephone interface to call you when anything goes wrong, with auto forwarding to your e-mail account if the line is busy.OH! Im sorry! You just wanted to know what is kicking your breaker.Sorry I got off on a tangent.My type of people sometimes do that.

If I could run,jump, or swim, I would be in the USA.

Accept or forget.Dat's my motto.

Juan

Congrats on your certifications.Very Impressive,however, they are all vehicle based,not residential or commercial.I am sure you are a very good technician in your field of expertise, and I will not foray into your field.I know next to nothing about Emergency Vehicle A/C systems.Although vehicle A/C uses the same principles,EPA does not recognise vehicle cerification the same as commercial or residential.The reverse is also true.There must be enough differences to justify seperating the fileds.

I do know that vehicle compressors use a HI LO pressure switch to turn off compressor clutch when pressures are out of tolerance, and some high end residential units also trip out on head pressures.What if you had a vehicle that was tripping out on High head pressure? What would be your first suspects?Clogged condensor coil?Freon quantity or type(someone could have put in freon 22 instead of 12 or equivalent.) Air or other non condensables in system? It is very hard to diagnose a pig in a poke,but 10 minutes with guages and a meter could reveal a lot.

These are things I have encountered in 30 years in the A/C business.

No disrespect for your knowledge or qualifications was intended.My apologies for possibly implying such.

Thank you for your reply. No apologies needed. You of course are correct, the pressures are the information we all need to stop guessing, and make a solid diagnosis.

check for a loose wire a good chance right at the breaker if discolored clean and redo

nick

Qc.ca

Hi. First, thanks for all of the responses. The unit is a Kenmore Coldspot,

Model #106 8722530, Serial #E21465213 (could be E21455213).

The last year Sears used the Coldspot Brand was 1977, so the unit is very old, indeed, and the SEER rating was probably unheard of. It is a very inefficient unit,and a new unit would give a fairly rapid rate of return, not to mention the green factor.I don't know how many btu's it is,but a qualified A/C Tech. or installer can do a calculation based on the heat load of your home, which takes into consideration the square footage, the number of windows, and their area,the amount of insulation in the ceiling and walls,the degree-days in your area, and many other factors.It is important to get the proper size unit for efficient cooling.A unit that is too large will cool the house too quickly, and will not have time to remove the humidity from the air.You will have to set the thermostat lower to feel comfortable, and the unit will be cycling needlessly, and the temperature will fluctuate.A unit too small, on the other hand will never be able to handle the heat load and reach setpoint, and will run excessively.A properly sized unit will run long enough to remove excessive humidity, and a higher temperature will actually feel cooler because of this factor.You will have less losses because of this, and a lower utility bill.

Hope this helps you to make a decision.

HTRN

!977, huh? Geez... When the unit runs, it REALLY cools down the entire house (small) quickly. No strange sounds coming from it. If I could find one, would it be worth the effort and cost to check the capacitor? I don't know if it's a single or dual capacitor. A qualified AC technician would have to do it. I'd have no idea. The unit is rated at 25,400 BTUs. Thanks.

There seems to be an abundance of qualified residential A/C specialists here. Perhaps one of them would be good enough to take a shot at replacing that cap for you? If you are in South Fla, I would not mind doing it for you. Does that model have the motor in the back, like a Corvair?

Used to be in East Central Florida (Melbourne). Am now in the East Bay, Northern California (Antioch, about 50 miles due east of San Francisco as the crow flies). Thank you VERY much for the kind offer, however!

From personal experience, 20 amps seems a little low for that many BTU's.

( A little over 2 tons) Check the data plate for the run amps and post to this blog.

Also, if you discover that you need a larger breaker, make sure the wire is large enough to carry it. A # 10 AWG will carry 30 amps, a #12 AWG, only 20 amps.

The breaker is there to protect the wiring, not the A/C unit.

HTRN

Come on, quit the double talk. Are you trying to tell him that his warranty is no good?

"He measured the amperage draw during "fan only" operation (1.60-1.85 amps) and when the compressor kicks in (11.00-13.20 amps)."

Sounds like the start cap is doing it's job.

"After a SHORT while, however, the amperage draw when the compressor kicks in is massive. We saw readings of up to 70 amps for a split second."

Now it sounds as if the current relay is sticky and/or a run cap has failed.Anybody been tinkering with this dinosaur?

Cleaning the coils is rarely a waste of time though.

The best advice here is to replace it (1977 vintage right?)Even if it is only 1997 vintage.The cost to repair will not be smart money.

Otherwise get fire insurance.

Yeah I know,it was working fine before.And it doesn't make sense to spend all that money on another unit if it's just some dumb little thing going haywire.Except that a new unit will work better and is less likely to burn your house down.

People at work would ask me...ohhh can you tell me how to fix the outlet in my house?I finally came up with a glib little line.You can do a little carpentry around the house and maybe a wall isn't exactly straight.You can do a little plumbing and end up with some drips.Or you can tinker with your electricity and end up causing a fire.

Pardon my vent .

You should try to use MCB with Thermomagnatic charactaristics D, it is espicial designed for motors with high kick off current. hope this will solve your problem.

OK, lets reset and forget all the stuff that does not pertain to you.

1. You are obviously in the US, so forget ALL of the above posts that refer to "MCB". Those are IEC (European) style devices, not applicable to the US.
2. A simple Search on a 24,500 BTU window AC unit comes op with an average of 12.5A FLC, with a 20A MAXIMUM circuit protective devices, so DO NOT put in a larger circuit breaker. In addition, Circuit Breakers primarily protect the WIRE, not the device. So unless you REWIRE THE CIRCUIT, increasing the breaker size would be ILLEGAL!
3. If it worked for a while and lately started tripping eventually, that is usually an indicator of the fact that something is wearing out or not functioning correctly any longer; a capacitor, a bearing, a recirc valve, something of that nature. So that is the first determination you must make; is this a new problem, or a new installation? If it is a new problem in an old installation, then proceed as some of the above suggestions indicate; looking for problems in the AC unit. If it is a new installation, then there is likely another problem.

IF it is a new installation (even if it is an old AC unit), then another possibility is that you have the wrong circuit breakers feeding it. MOST 20A breakers in the US for residential use now have what is called a HACR rating, short for Heating, Air Conditioning and Refrigeration. This means they have different trip settings that can handle the starting current of AC motors, particularly hermetically sealed compressor motors, because they tend to act exactly as you describe. But in the "olden days". breakers did not automatically come with HACR ratings, you had to order them that way. IF your electrician was unaware of that and hooked up your 20A outlet to standard (non-HACR rated) breakers, the fix may be as simple as replacing them with the CORRECT breakers.