Strange intermittent A/C issue


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Old 07-08-17, 05:21 AM
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Strange intermittent A/C issue

Here's the problem. Happens intermittently (last time was this morning at 2AM).

A/C stops cooling yet the compressor fan outside continues to run as if all is OK.

Here's what's been done so far:

Unit has 2 capacitors, one tested fine the other was replaced.
New Fan motor (repair guy thought maybe it was overheating and shutting down the compressor)
Condensate drain is clear and drain switch tests OK.
Refrigerant is fine

Problem is, every time the repair guy comes out it is working again. It stops cooling usually for a couple hours at random times. Sometimes it can go for 2 weeks without issue then it happens again.

It's an 8+yr old Carrier heat pump unit model 25hcb324A. When it is working it cools perfectly so it isn't a refrigerant issue. Compressor fan runs as if it the unit is cooling but it's not.
 
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Old 07-08-17, 05:35 AM
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Since you are in NJ I will assume you have a standard furnace inside and an A/C/heat pump outside.

I am not an HVAC tech so I am just shooting from the hip. It is possible the compressor in the condenser outside has thermal overload protection built in. I think your guy was right thinking it was overheating, but I do not see why he would change the fan motor if the motor was running fine. I think the issue might be the compressor.
 
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Old 07-08-17, 05:38 AM
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When it stops cooling, is the inside blower still running (is a normal amount of air coming out of the ducts)? Also, you mentioned that when it stops cooling, the compressor fan is running, but is the compressor running? You mentioned that the compressor fan motor was replaced. Is the replacement the same specs as the original (speed, horsepower), and is the fan blowing air out the top of the unit? If the compressor fan is running too slowly, or is blowing the wrong direction, the compressor could be overheating and thermally shutting down.
 
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Old 07-08-17, 06:11 AM
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@Tolyn Oooops, sorry, we are now retired in central Florida. Have to change my profile.

@Bob14525 Everything is "normal" except it ain't cooling. INSIDE BLOWER is working just as it is when working OK, fan was replaced with same spec fan (1/4hp 825 rpm) spinning in the proper direction. I assume the compressor itself not to be running because the cooling "pipe" going under the house isn't cold when this occurs but the compressor fan is running. When it is OK that pipe is quite cold and sweaty.
 
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Old 07-08-17, 06:34 AM
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This is a longshot, but you might want to check the power connection at the compressor. They usually have a "plug-in" connector that attaches to terminals on the compressor. If you get a poor connection, they get hot and sometimes the compressor terminals will literally burn away. Be sure the power to the outside unit it turned off (there should be an outside power disconnect located near the outside unit) and wear safety goggles as there is pressure inside the compressor. While it's remote that the compressor would leak by removing the power connector, it's better to be safe than sorry.
 
 

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