Central air won't cool at night

jtwtechJuly 15, 2011

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.

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

    Bookmark   July 16, 2011 at 1:49AM
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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.

    Bookmark   July 16, 2011 at 2:16AM
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Is this a heatpump?

    Bookmark   July 16, 2011 at 4:58PM
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Have you checked to see if there is ice forming on the inside coil at night?

    Bookmark   July 16, 2011 at 11:19PM
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It is not a heat pump, and no I have not checked for ice at night. I'll do that in a bit.

    Bookmark   July 17, 2011 at 1:50AM
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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?


    Bookmark   July 17, 2011 at 9:40AM
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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.

    Bookmark   July 20, 2011 at 3:28PM
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