HELP!! a/c just stopped working

the4of_usAugust 14, 2007

hi everyone, just came home and noticed the a/c stopped working. at what time and for how long i don't know, we left at 3pm and its now 10:30 pm, it was working when we left.

it has been a cooler day then past, i think it was 89-91 today, all last week we were in the 100-108.

all breakers (that i know to look for are still in the "on" position.

what information do you need from me to help me to diagnose this.

we have a heat pump that (as far as i can tell) worked perfectly, last week when it was 102, the house was at 74 and didn't fluctuate at all, didn't notice any strange noises or that the unit was working differently (although i bet it was working hard, just simply due to the temps)

let me know what info i should post and please give me your thoughts.

thank you.

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Well, I'm not a hvac guy, but I'll start with some questions that they will want:

Does the fan inside run (blowing non-cool air)?

Does the outside unit appear to be running?

In other words, does the unit appear to be running and just not cooling, or is the unit actually not even running?

If the unit isn't starting, there are various relays that can get stuck, or stop working. I had an older unit (waiting to be replaced) with a failing relay that I could get to work again just by turning off the power to the unit for a minute, and then turning the power back on.

If it is running, and not cooling, then it could be a coolant leak.

    Bookmark   August 15, 2007 at 10:43AM
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"If it is running, and not cooling, then it could be a coolant leak"

- or blocked/reduced air flow accross the evaporator (inside) coil caused by a dirty filter or dirty coil.

    Bookmark   August 15, 2007 at 10:51AM
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thanks for your replies

the unit is not running at all. i had an electrician stop by on one other issue and had them check to see if i had power.
apparently there is power going to the unit.

the breakers are functional, power goes to the sub disconnect and to the a/c unit. after that he couldn't help. he said it could be the motor, or a mother board??

i have no readings on the 2 digital thermostat's and they don't need batteries (as it appears to not have any)
so far, it is as if someone pulled the plug..

i have a zone splitter, anything i should look for there.

everyone I've called is 2-5 days out

    Bookmark   August 15, 2007 at 11:46AM
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No readings on the thermostats is a clue. Can you check and see if the 24 volt transformer is working?

    Bookmark   August 15, 2007 at 12:14PM
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i have a tester..., just don't know where or what to test?

    Bookmark   August 15, 2007 at 12:18PM
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Try something simple: Turn the system OFF at the theromstat. Wait a minute and turn it back to Auto/On. A simple reset like this works for me in my 18 yr old system.

    Bookmark   August 15, 2007 at 2:01PM
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Did you get this fixed? What was it?

    Bookmark   August 20, 2007 at 2:15PM
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first off thanks to everyone for your help.
sorry i couldn't post was too hot upstairs where the computer is (100+).
any who, TECH came out and was puzzled for a moment, but then fund out we had/have a shout in the mini zone board. he managed to tap it and get it working. (YES!!! THERE IS A HVAC GOD!!!). so now i have found a replacement (brand new) on the Internet. i think I'm going to try and tackle the project myself. un-wire and re-wire the board **seams** straight forward.
what do you all say.

    Bookmark   August 21, 2007 at 2:34AM
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Disconnect all power so you don't blow the small fuse in the 24-volt system. Blowing the fuse is easy to do if you spark low-voltage wires in the air handler or at the t-stat that still have power.

Best of luck.

    Bookmark   August 21, 2007 at 8:35AM
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