Air Conditioner cycles off after 3 to 5 minutes---need troubleshooting help

I have a 20-year old Frigidaire through the wall air conditioner.

When first turned on it does a great cooling job. A digital thermometer right at the outlet is showing 40=B0F.

After three to five minutes, the compressor turns off and the cooling stops.

After maybe 5 minutes the compressor comes back on and cools for another 3 to 5 minutes.

I took the unit outdoors and cleaned the fins with a garden hose and a fin-cleaning aerosol spray. It is difficult to view the fins visually, but I'm fairly sure they are clean. The cleaning did not seem to change the cycling time at all.

I'm in a small town and it is a heat wave. It is difficult to get a repair person in the best of times---and I'd rather save the money and repair it myself if it is something I can handle.

How do I troubleshoot from this point?

Reply to
Bob
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When first turned on it does a great cooling job. A digital thermometer right at the outlet is showing 40°F.

After three to five minutes, the compressor turns off and the cooling stops.

After maybe 5 minutes the compressor comes back on and cools for another 3 to 5 minutes.

I took the unit outdoors and cleaned the fins with a garden hose and a fin-cleaning aerosol spray. It is difficult to view the fins visually, but I'm fairly sure they are clean. The cleaning did not seem to change the cycling time at all.

I'm in a small town and it is a heat wave. It is difficult to get a repair person in the best of times---and I'd rather save the money and repair it myself if it is something I can handle.

How do I troubleshoot from this point?

+++++++++++++++++++++++++++++++

I'd call a HVAC company and get on the waiting list. This heat wave is brutal.

20 years old?
Reply to
Master Tang

When first turned on it does a great cooling job. A digital thermometer right at the outlet is showing 40°F.

After three to five minutes, the compressor turns off and the cooling stops.

After maybe 5 minutes the compressor comes back on and cools for another 3 to 5 minutes.

I took the unit outdoors and cleaned the fins with a garden hose and a fin-cleaning aerosol spray. It is difficult to view the fins visually, but I'm fairly sure they are clean. The cleaning did not seem to change the cycling time at all.

I'm in a small town and it is a heat wave. It is difficult to get a repair person in the best of times---and I'd rather save the money and repair it myself if it is something I can handle.

How do I troubleshoot from this point?

************************************************

At 20 years, I'd be out looking at new, more efficient units that are the same size or smaller to fit in that hole.

Reply to
Ed Pawlowski

I'd do the fin cleaning routine, again. That's my best diagnosis, from here.

Reply to
Stormin Mormon

Bad thermostat ( short cycling) Low on refrigerant (cycling on a low pressure switch) Dirty or bad condenser motor (cycling on a high pressure switch)

All 3 are easy to troubleshoot if you have any knowledge of basic electricity. Just find the appropriate terminals and wire the control out.

In this heat wave and your 3 to 5 minute cycle I am betting on the thermostat.

Reply to
Big Bob

Sometimes the overload relay on the compressor will become overly sensitive due to corrosion and or erosion of the contacts which will create a resistance which in turn will create heat which will case the overload relay to click open. When the AC starts and stops, do you hear a "click"? If so, that would be the overload on the compressor. It should be easy to replace. You have to check the supply voltage because that's another thing that, if low, can trip the overload.

TDD

Reply to
The Daring Dufas

I'm with Ed. You should be able to get a new unit that will pay for itself fairly quickly in energy savings compared to a 20 year old unit.

Reply to
cjt

Youve done all you can as a homeowner . Its time to call for a professional diagnosis..but i wouldnt dump alot of money into it. 20 years is over the average life expectancy...and especially if you live in a southern state.

Reply to
ilbebauck

Tomorrow is my day to work on this again.

As to the 20 years.....this unit has actually been used very little, and has been well protected during the off season.

Here's why I'm reluctant to just dump this air conditioner and buy something else (aside from being short on cash): when the air conditioner is turned on, it is quiet and smooth and cools the output air to 40=B0 F immediately. To me that seems like all the internal parts are doing their jobs well and something external (like a control or heat exchanger) is causing the cycling. If it is low on refrigerant would it cool to 40=B0 so quickly? Same with dirty or bad condenser motor?

I could see the thermostat being the problem or the fins are still not clean enough.

Is my logic correct? Is getting to 40=B0 quickly really telling me that certain parts are OK?

Incidently, the parts drawings for this unit are still on the web at:

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It was 102=B0 here today and forecast hotter tomorrow.

B.

Reply to
Bob

Looking at the wiring parts list that you provided, i see no mention of hi or low pressure refrigerant cutoffs. If the motor continues to run and it is the compressor kicking off, the problem is going to be the thermostat or as pointed out by another user, an external overload under the compressor cap. If the entire unit is kicking out, that is, the fan and the compressor, you could have a faulty thermostat or selector switch. Without being there, this is the best I can do for you. 40 seems a bit cool but is possible. You stated that you removed the unit and cleaned the coils. I assume you cleaned both the evaporator and condenser coils. Also make sure the filter is clean. As stated in my previous post, my bet is on the thermostat.

As to the 20 years.....this unit has actually been used very little, and has been well protected during the off season.

Here's why I'm reluctant to just dump this air conditioner and buy something else (aside from being short on cash): when the air conditioner is turned on, it is quiet and smooth and cools the output air to 40° F immediately. To me that seems like all the internal parts are doing their jobs well and something external (like a control or heat exchanger) is causing the cycling. If it is low on refrigerant would it cool to 40° so quickly? Same with dirty or bad condenser motor?

I could see the thermostat being the problem or the fins are still not clean enough.

Is my logic correct? Is getting to 40° quickly really telling me that certain parts are OK?

Incidently, the parts drawings for this unit are still on the web at:

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It was 102° here today and forecast hotter tomorrow.

B.

Reply to
Big Bob

Please take the cover off the unit. And clean the condensor (the hot radiator in the back). Inside and out. You may need somthing like a tooth brush to get the inside surface of the coil. Use detergent and hot water. Rinse well, with a water hose. Reassemble.

Low charge can cause lower temps. But, the quick cold action suggests the compressor is doing its job.

Reply to
Stormin Mormon

My suggestion of the overload was because of the age of the window unit. If he cleans it and it still does the same thing, it's probably the overload. A few months ago, my friend and me cleaned an old unit he had in a front room of his home. After cleaning, it was behaving the same way as the OP's AC. It turned out to be the overload relay under the connection cover of the comp. I found a link that can explain it better on, of all places, a coke machine page.

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TDD

Reply to
The Daring Dufas

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......and here's what I found today........

I by-passed the thermostat and the cycling seems to have stopped.

I did look at the coils again, both by checking airflow and shining a flashlight through the fins, and I'm pretty sure the coils are plenty clean.

Next challenge:

I looked at Frigidare replacement parts and the thermostat is in the $110 range----ouch!!!!! The Frigidare part # is G158995.

Looking further on-line I found a universal replacement thermostat for about $35 at

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Does anyone have any comments on using a universal part to save some cash?

My air conditioner is 220 volt. Looking at the wiring diagram it looks like the control circuits are also 220 volts, In the various online parts catalogs I don't see any callouts for voltages for thermostats. Am I missing something here?

B
Reply to
Bob

Not only is the voltage important, so is the amp rating. The specs for the part you propose are: Universal type window unit thermostat kit.

Range: Cold Off (52ºF) Warm On (93ºF) Diff: 6ºF Capillary: 18" End 1" Aircoil SPST, F.L.A. 20A, L.R.A. 80A

I would go for it

--------------------**********************-------------------------------------------------------------------------------------

......and here's what I found today........

I by-passed the thermostat and the cycling seems to have stopped.

I did look at the coils again, both by checking airflow and shining a flashlight through the fins, and I'm pretty sure the coils are plenty clean.

Next challenge:

I looked at Frigidare replacement parts and the thermostat is in the $110 range----ouch!!!!! The Frigidare part # is G158995.

Looking further on-line I found a universal replacement thermostat for about $35 at

formatting link
Does anyone have any comments on using a universal part to save some cash?

My air conditioner is 220 volt. Looking at the wiring diagram it looks like the control circuits are also 220 volts, In the various online parts catalogs I don't see any callouts for voltages for thermostats. Am I missing something here?

B
Reply to
Big Bob

Before you spend money. Try spacing the long tube (from the thermostat) away from the evaporator. About 3/8 to 1/2 inch or so. If the sensor tube is touching the cold coils, the sensor may get cold before the air temp indoors is cold.

Reply to
Stormin Mormon

That's a reasonable web page. Like the writer says, Klixons mostly all look alike. When I think Klixon, I think start relay, not overload. Oh, well.

Reply to
Stormin Mormon
[snip]

It was 102° here (northeast Texas) yesterday. Now we're having a cold wave, where temperatures are dropping to 97°.

Reply to
Mark Lloyd

Hey Big Bob (from Bob);

I love the education I'm getting. Where did you come up with the specs for the Universal type window unit thermostat kit?

SPST=3D single pole, single throw. What is F.L.A. and L.R.A.?

Is it Universal enough that the mounting holes are going to match, or is that too much to ask?

Stormin Mormon: The tube spacing looks OK, but before I spend buy any new parts, I am going to try moving the tube somewhat and see what happens.

Bob

Reply to
Bob

SPST= single pole, single throw. What is F.L.A. CY: Full Load Amps

and L.R.A.? CY: Locked Rotor Amps.

Stormin Mormon: The tube spacing looks OK, but before I spend buy any new parts, I am going to try moving the tube somewhat and see what happens.

CY: Sounds like a plan. No sense in replacing a good part.

Reply to
Stormin Mormon

Did you install a jumper wire in place of the thermostat? If the AC ran OK with the jumper in place, then it's the thermostat. The way thermostats are mounted on window AC units is important because it also detects icing of the evaporator and shuts off the compressor. The rubber or foam block that the sensing bulb is mounted on is necessary for proper operation.

TDD

Reply to
The Daring Dufas

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