Split Air Conditioner Problem

You need to measure the current draw of you compressor.

during the 5minute run of the compressor, the current drawn by the a.c is about 9.5A. but at the end of 5 minutes when the compressor just trips the current rapidly shoots from 9.5 to 20A. i measures the currents using clamp meter. i think the compressor just trips on its overload protection when current reaches 20A. but it remains off for about 30 minutes while the room temperature have exceeded much above the temperature setting in A.C

Ok. Now see posts 3 and 7.

Your compressor is seizing...when the overload trips it removes the compressor from the circuit to keep it from melting the wires and/or exploding....What are the running load amps stated on the tag? It sounds like it's low on freon or the run/start cap is weak.....You need a capacitor tester to test it....or you can change it out with a new one...the overload is a thermal device, the compressor should be very hot to the touch...it relies on the freon for cooling, which is why it will overheat on a low charge...If the capacitor is good and proper strength, and the charge is set correctly, and the wiring is in good order, than it sounds like you need a new compressor...

the tag current is 9.5A. i checked with multimeter the run/start cap of the compressor. it is perfect i.e. 45UF. the wiring in outdoor unit is also intact. no meting etc. water however is dripping from indoor evaporator pipes.

LOCKED ROTOR, its all done

what does that mean? how is rotor locked if compressor is running for 5 minutes after each 30 minute off time???

Locked rotor wouldn't let it run for 5 minutes, it would be an immediate trip!

Compressor motor running empty or dry running usual heats up fast, so it will trip the thermal safety. Safety first.

You could have liquid refrigerant getting back to the compressor, causing the jump in current draw. As others have said, check the filter, evaporator coil and anything else that could be blocking air flow across the evaporator. Then call for service. You will ruin the unit if you allow it to keep doing this - if you haven't already.

Does it have any filters that may need cleaning?

indoor unit filters are super clean. there is however some dust on evaporator and air louvers.

service call time, bring your wallet

Is your condenser flooded type? Does it have a reservoir? If yes, then you might have a pump problem. Condensate reservoir usually has a high level switch, which is interlocked with compressor switching. Some units does not run during full level reservoir, to let the condensate evaporate first, when low level is reached then it runs again. -- This is common fault during humid weather or full load and if reservoir pump is defective, or level sensor fault/defects/loss connection.

Also, if you could spot a difference of the sounds of the compressor from previous then now, it would be helpful. An empty running sound would mean, you have a refrigerant leak-and system is running low with it. Compressor is equipped with Thermal safety device, as it heats up, it triggers to protect the compressor motor winding burnt out.

See manuals for trouble shooting tips.

You need to check if it is going off on control voltage or overload....it might be overheating from low freon charge, or a pressure control either high or low....If it's going off on overload the contactor will remain engaged....if the contactor is releasing you have a low voltage interruption...If the compressor is going off on overload the fan should continue to run...If the fan is shutting off too, then you need to check for control voltage, and if none then trace it to the control that's interrupting operation....the compressor may have an internal or external overload....you can put your hand on the compressor, if you can't hold your hand on it, it's overheating...When it's running the suction line should be sweating all the way to the compressor....

....or you could just call a service mechanic....my recommendation...

Quote "My 1.5ton,230volt split ac was running fine for past 2 years .but from yesterday it started problem. the compressor remains on for about 5 minutes whatever the temperature setting is and then turns off and remain off for about 30 minutes "

Are you saying that the compressor runs after the temperature setting is reached on the thermostat? Check thermostat

I see nothing wrong with the compressor remaining off for 30 minutes. I wish mine would. Does the unit maintain the temp setting in the house or does the house heat up?

it sounds like a thermal overload trip but as usual with so little info I just suggest a service call

the house heats up , but the ac remains off for its fixed time of about 30 minutes. it the house would not heat up, then i would have no problem. the room temperature keeps on increasing but compressor is not coming .

If you continue through these cycles, you will seriously damage you compressor, if you haven't already. The compressor starts to shed insulation and it gets to the expansion orifice and no further.

It sounds like you're low on refrigerant!

Call an HVAC tech. A reputable one!

There are lots of places doing "FREE" check ups on HVAC units so they can tell you you need $5000 worth of extra work.

Immediately after the unit trips, determine the temperature of the room. Note this temperature for later reference. Then deenergize the power circuit to the AC unit. This may be accomplished either at the control panel, breaker box or by simply unplugging the unit if it is connected to a wall receptacle.

Test the unit to be sure it is de-energized and safe from electrical shock should anyone touch any internal uninsulated wires or terminals.

Wait one hour. Note the room temperature again.

Reenergize the unit, note the amp draw and let it run until it trips. Then note the run time, amp draw and the temperature of the room, again.

Now, this is important!

CALL A REPAIRMAN! NOW!

When he arrives, give him the information you have recorded. He will recognize that you are a smart man and will not try to cheat you.

More than likely you have developed a leak and the refrigerant is low.

Get a professional repair service to look at it before it is too late to save the compressor.

Have you checked tnat the outdoor fan is running when the compressor is in operation? It may simply be a fan fault causing the compressor to go out on pressure switch.

the outdoor fan is running ,however the fan speed seems a little slow. yet it is running all the way.

Isolate it, take it off, clean it thoroughly and lubricate the bearings, then, and then re-assemble. Then report back.

Brilliant, this site, isn't it? :-P

Spades has a good suggestion. In the opposite direction, loss of refrigerant could cause the compressor to shut off on low pressure, which with low charge could take a while to build back up. Inspect the system for oil drips or spotting, which could indicate a leak of refrigerant, oil, or both.

first clean the condenser on the roof, you can use a power washer but be careful you do not close up the vert fragile aluminium vanes. I suggest that if you do use a power washer, the movement is up and down and not left to right.

Second, get the gas topped up, or checked at least, then aske the A/C guy to check the motor start capacitor.... they do tend to pop in warm weather.

Third clean out your indoor unit, take the fliters out and wash, clean the evaporator with VERY hot water.

Fourth make sure that the black insulation on the pipework is in place and covering all the pipes to the evaporator.. that could be a source of the condensation.

And last.... turn up your unit by 1 or 2 degrees.. until you have a comfortable temperature. You don't need the room to be a walk in freezer.. 21 to 24 C is a very stable and comfortable temp for the general rooms, slightly lower in the bedrooms.

The care with which evaporators and condensers should be cleaned is worth emphasizing.

If in the process of cleaning, you bend fins, you may have made things worse, not better.

If you force gunk between the fins, you have probably made things worse and are likely tempting yourself into risking damage to the heat exchanger with attempts to remedy.

If you use a strong cleaning agent and degrade the material you will definitely made things worse. Using something like wheel cleaner is definitely a bad idea. Hot soapy water will work adequately.

Of course any gouging, punctures, or cracks created in the heat exchanger are not an improvement over a dirty but sound heat exchanger.

The care with which evaporators and condensers should be cleaned is worth emphasizing. If in the process of cleaning, you bend fins, you may have made things worse, not better.

did I not say that?

If you use a strong cleaning agent and degrade the material you will definitely made things worse. Using something like wheel cleaner is definitely a bad idea. Hot soapy water will work adequately.

Cold water will work fine! Soap will react with the fins and copper, on cheaper units soap will also have an effect on the motor and fan, and as the outside unit is exposed to the elements, water is the safest bet.

The reply theme here is.... get a guy who knows what he is doing! You cannot make someone an A/C tech with a few paragraphs of text.

'Did I not say that?'

Not sure, but I did read you mention something close. It is important enough to warrant emphasis, which is what I wrote.

It is not uncommon for people to damage their evaporator coils/heat transfer fins this way.

It wasn't a rebuke or an attack on your statement...just emphasis. Relax. If I wanted to be critical of your comment, I would have noted something like pressure washers are far too powerful to use...by the time you find the right distance, damage would already be done.

.

Okay, so I'm curious about the corrosion of copper with mild soapy water. Care to enlighten me?

Coolyar, you haven't said much about what your condensor (outdoor unit) is doing.

Is the condensor fan spinning at the right speed and blowing warm air out? Is the fan and the condensor clean?

Sounds like a condensor problem to me where the unit runs fine for a short time but the condensor doesn't condense the refrigerant and you trip off on high pressure after 5 minutes then after 30 minutes it equalises and tries again.

With water dripping from the evaporator (indoor unit) you want to check the condensate drains or try closing the doors and windows.

Do you have manifold gauges?

when the compressor turned on after 30 minute off time, i just went outside to observe the outdoor unit fan behaviour during running. the compressor and fan ran for about 4 minutes perfectly. chilled water droplets were present on pipe lines. outdoor unit fan was blowing hot air. but after 4 minutes, the fan started to slow down and stopped completely within 10 seconds. after the stopping of outdoor fan, the compressor was running for about 30 seconds and then the compressor also tripped. overload protection is inside the fan.

i think that main problem is weak capacitor of outdoor unit fan due to which fan stops and then stopping of fan also causes heating of compressor and hence its tripping. but do not know for exact.

there is no sign of oil/grease leakage in any piping /part of indoor and outdoor units.

That looks like a starting cap not a running cap.

Condensor fan stopping is your culprit. A failed motor bearing perhaps.

Condensor fan and compressor run at the same time, If the fan stops then HP trip out of compressor is imminent.

Agreed.

Replacing the fan should do the trick.

Change the fan motor AND its capacitor(they are relatively cheap) before trying it again! Allowing a compressor to repeatedly cycle on its overload severely stresses it.

The fan motor is bad....make sure you get the right motor, hp, voltage, rpm, rotation, mounting, sealed motor, probably ccw...and a new capacitor....also make sure you mount the blades in the proper position and orientation relative to the shroud...check the blades for damage and proper pitch and balance...you may need a new fan blade as well....fan blades sometimes suffer loss of pitch angle from rain and other obstacles...

WAL... You have to be careful with your suggestion regarding manifold gauges. While you might be capable of connecting said gauges, you do not know if the OP is... you can take it that he is not qualified to work on any type of A/C unit, if he was he would not have asked the question, therefore my advice to you both is this..

DO NOT ATTEMPT ANY WORK OTHER THAN TO CHECK WHAT YOU CAN!

Unless you have been trained properly to fit gauges, then you should not attempt it, and disregard any suggestion to do so.

Get a qualified and highly proficent A/C company to look at your unit.

Health and Safety Warning with regards to refrigerant gases.... IT WILL KILL YOU!

here are diagram of indoor/outdoor units

Whoever did rates you GA here is messing with you. Regardless of circuitry that your system operates, it does not matter. You must have to correct the mechanical first, other than doing the diagnosis on the electronics.

It is best advice you deal with the hardcore mechanics first of the system. Attacking it in its electronics, might complicate your problem, instead of simple trouble you got there. The lesser of chances that you would isolate the cause

The problem is not electrical.

Needs a complete service out, including condenser cleaning, possible evap cleaning and filters replaced or cleaned. -- JHF

Unfortunately we do not even have the courtesy of knowing the make and model number of the unit. While there are some valid troubleshooting suggestions in the above postings, the truth is the guesses are based on old pre-modern electronic control systems technologies. Modern high efficiency split systems are sensor based microprocessor controlled systems that use computer logic to determine the precise operating point given what the conditions are in real-time.

Whereas in the old electro-mechanical control days a fan slowing down was a sure sign of impending bearing or run capacitor failure, in today's system it is probably just the control system telling the variable speed DC fan motor to back off a bit because the compressor head pressure sensors indicate that the variable speed DC compressor motor can slow down a bit because the cooling load is approaching a new setpoint, or any of those control strategies that we wished we had but could not easily implement using fixed speed AC motors.

Today's systems are very easy to troubleshoot without any traditional tools, as long as you have access to the manuals, because all the operational parameters are available from the control system. Depending upon the age, make, and model number, all it takes is the proper sequence of control panel key presses to read the data, or perhaps a proprietary code reader that connects to the control system via the IR port or a dedicated connector.

Without this knowledge you are doomed. As Fredski and others have said, contact a factory trained technician, you're simply wasting your time in most cases, unless you can identify the source of the smoke emanating from the cabinets.