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Central air won't cool at night

Posted by jtwtech (My Page) on
Fri, Jul 15, 11 at 23:51

This is an ongoing problem, and I have posted on here before about it. No one seems to know what's going on. FWIW, I have not had anyone come to my house to look at this problem.

This has been going on for several years, but a real heat wave is here, and it's going to get uncomfortable. My house stays cool throughout the day, but when night comes the fan runs, but the outside ac unit ( I think this is called the evaporator? ) will not turn on. The a/c runs fine from morning until night. It has happened for as long as I can remember. I have gone outside to check the a/c and I can hear a clunk or clicking sound every now and then.

It's just so strange that it only happens at night, but it's like clockwork. Any ideas or help appreciated.

Follow-Up Postings:

RE: Central air won't cool at night

Just asking the obvious...what kind of thermostat do you have? If it is programmable, how is the program set?

RE: Central air won't cool at night

It is programmable. I have verified that it is not the thermostat. I changed the thermostat but also, our thermostat is usually on hold to maintain the same temp. Also at the advice of someone ( I can't remember exactly what I did at the time) but I shorted , If I remember correctly, R G and Y on the thermostat at night. Same thing, fan only ran.

RE: Central air won't cool at night

Is this a heatpump?

RE: Central air won't cool at night

Have you checked to see if there is ice forming on the inside coil at night?

RE: Central air won't cool at night

It is not a heat pump, and no I have not checked for ice at night. I'll do that in a bit.

RE: Central air won't cool at night


a nice anecdotal story with few facts.

let's get some specifics.

your location?

brand, mdl, age, size of existing system?

amount of living area unit serves?

home is sgl story or two story?

location of ductwork?

thermostat setting?

average high outside temperature?

insulation qualities of home?

filters regularly changed?

last time system was service?

any idea of supply temperature? if not, find out with dig thermometer. how about return temperature? if not find out.

why accept this situation without an experienced HVAC pro checking your system out?


RE: Central air won't cool at night

So your having a problem with your unit for a few years and haven't called anyone out? unbelievable. Your compressor sounds like its overloading. keep on running it and soon it will go poof. Up in smoke.

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