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Hello! New to the forum. I am no expert when it comes to AC systems, so please bare with me. I have a question about the AC in my small condo. The AC will cool the condo to the set temperature but will then stop cooling. The fan continues to run but won’t turn off and the temperature in the condo rises.

The thermostat is a Honeywell programmable unit installed 2 years ago, which replaced the original mercury thermostat. The condenser and evaporator were replaced in 2016. The rest of the components are the original from 1991. The system has worked ok until a month ago.

A tech has been here 3 times and can’t figure out the issue. Hoping someone on this forum might have some input.

Background: He was here a month ago. He checked the freon and said it was ok, maybe a little low, so he added some to top it off. He checked the pressure on both sides of the compressor and noticed it fluctuating pretty bad. He moved the TXV bulb at the evaporator(?), which seemed to help. The system seemed to work well for a month. Then 2 days ago, it started to do the same thing, cool to a point then stop cooling. The same tech came today and replaced the start/run capacitor. He checked the pressure and said it was not fluctuating today like it did a month ago. The system ran correctly for a few minutes while he was here. Shortly after he left, it started the issue again, cool to a point then stop cooling again. The system has been running for about 2 hours now and won’t cool the condo.

Turning the system off for a few hours and then turning it back on seems to help for a while, but the same symptoms begin again. Maybe some type of thermal protection?

Does anyone here have a possible reason as to why this could be happening and any suggestions how to correct? Any help would be appreciated.

Thanks!
 

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Hello! New to the forum. I am no expert when it comes to AC systems, so please bare with me. I have a question about the AC in my small condo. The AC will cool the condo to the set temperature but will then stop cooling. The fan continues to run but won’t turn off and the temperature in the condo rises.

The thermostat is a Honeywell programmable unit installed 2 years ago, which replaced the original mercury thermostat. The condenser and evaporator were replaced in 2016. The rest of the components are the original from 1991. The system has worked ok until a month ago.

A tech has been here 3 times and can’t figure out the issue. Hoping someone on this forum might have some input.

Background: He was here a month ago. He checked the freon and said it was ok, maybe a little low, so he added some to top it off. He checked the pressure on both sides of the compressor and noticed it fluctuating pretty bad. He moved the TXV bulb at the evaporator(?), which seemed to help. The system seemed to work well for a month. Then 2 days ago, it started to do the same thing, cool to a point then stop cooling. The same tech came today and replaced the start/run capacitor. He checked the pressure and said it was not fluctuating today like it did a month ago. The system ran correctly for a few minutes while he was here. Shortly after he left, it started the issue again, cool to a point then stop cooling again. The system has been running for about 2 hours now and won’t cool the condo.

Turning the system off for a few hours and then turning it back on seems to help for a while, but the same symptoms begin again. Maybe some type of thermal protection?

Does anyone here have a possible reason as to why this could be happening and any suggestions how to correct? Any help would be appreciated.

Thanks!

If the AC unit has a fan setting for Auto (or even a complete Auto setting) then use that because if the fan continues to run after the cooling mode stops that can raise the temp.
 

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Hello. This problem can be sorted out after a visit. Strange a technician came 3 times but he could not fix the problem. If you want I can send over a very expert and professional technician. he got the job offer from Ontario Green. I am pretty sure he will sort out the problem.
 

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While diagnosing over the internet is risky at best, I'll offer a few ideas.
First, the thermostat, that's what it does shuts off the cooling at the set point. If the condenser fan keeps running, then that possibly could be the compressor going bad or the compressor actually overheating., or bad overload, which means a bad compressor.
If everything outside stops that sounds more like a thermostat switch or furnace control board relay going bad, contactor bad etc.
Second, the hunting pressures, likely was a low charge, he should have caught this if you had low sibcoolong. Not having a solid column of liquid at any expansion device will cause hunting. If your sys has run correctly before, that's a good sign that it was in the right place.
Also, he should have checked all wiring for loose connections before replacing or moving anything.
 
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