Central Air Stopped working, Thermostat went blank?

Hey all,

My central air stopped working completely this evening (its less than a year old). My thermostat went completely blank (it is not battery operated). I checked the fuse box and they weren't tripped. I checked the box (circuit box I think) by the AC unit and it didn't have any fuses. I cant even get the fan to turn on in my house.

If I throw batteries into my thermostat then the thermostat will "act" like it is turning on by showing me a green light. When I go outside however, the unit is doing nothing.

What on earth could cause this. I need to fix this because it will be 98 tomorrow and I dont feel like frying!!!! Thanks


The thermostat is hard wired but there was a spot for batteries. The thermostat worked with out batteries. When I took the cover off I saw the slots for the batteries so I placed them in there and the thermostat came back to life, but the AC still wont turn on. The thermostat show the AC unit is on, but when I go outside to check it out, the unit is completely dead.

Update 2:

It ended up being water in the pan and it triggered a shut off. The guy told me that if it happens again to just shop vac the water out of the pan. Its nice to have my AC again :-) Thanks for all your help.

10 Answers

  • 1 decade ago
    Favourite answer

    For some reason it looks like you are not getting voltage to the thermostat. Without this voltage, you will not pull in any relays to fire the AC system. If could be that the power supply went out or blew a fuse in the control section of the system.

    Since the unit is so new, I would call the shop that put it and have them out to repair the system. Let them know that it doesn't work. They may be able to give you some advice over the phone. good luck.

  • Anonymous
    4 years ago

    Digital Thermostat Not Working

  • 4 years ago

    Thermostat Not Turning On

  • dee
    Lv 5
    1 decade ago

    You could have any number of problems from something very simple to something more complex. Simple - the thermostat has either lost its programming or is broken. The complex - something is wrong with the unit itself.

    If it is fairly new, the unit (not the thermostat) is probably still under warranty (labor may or may not be covered depending on if you bought an extended labor contract or not). You don't sound qualified to do any serious trouble shooting (sorry, but that's the truth) so don't take a chance on voiding your warranty by trying to fix it yourself. Call a tech. The only other alternative is to continue to sit there and swelter in the heat.

    Source(s): 20 years working for a major manufacturer of central heating and air conditioning equipment
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  • 1 decade ago

    Once an AC unit turns off, it should stay off for at least 15 minutes before starting.

    I thought said the thermostat does not work on batteries. Then you said you placed batteries into it.

    If the batteries went dead and were like that too long, you have to re-program your thermostat.

    get out your instructions that came along with the thermostat and follow them.

    If you do not have the instructions, do a google/yahoo search on the model number of thermostat (model number +setup)

    If this does not work call service as the first answer stated.

    Good Luck

  • Anonymous
    1 decade ago

    TRUST ME. Transformer in your furnace most likely went bad. Some of them have a reset button. Some of them just have to be replace. The transformer steps the voltage down from 120V to 24V. That 24V provides the power for all of your controls including your electronic thermostat.

    One other thing. My 19 month old daughter often turns the switch off on the side of the furnace. The furnace is in the laundry room and she is down there with her mother a lot. This will cause the same symptoms that you have described.

  • Anonymous
    4 years ago

    For the best answers, search on this site https://shorturl.im/hllHj

    the things to check are 1 circuit breaker for outside unit...2 capacitor on on outside unit could be bad...if it is swollen or is oily it is bad...3 bad contactor ....if the inside unit is running there should be a buzzing noise on the outside unit..this would be the the contactor energized..if it is buzzing then 1 no power 2 bad capacitor.... if it is not buzzing 1 bad contactor 2 low freon pressure switch could be bad(was it coooling good before it quit coming on ) if yes then low freon will not be the problem 3 broke thermostat wires close to outside unit...

  • 1 decade ago

    It was 103 here today. I would not wait for more than minutes when my air went out. I immediately call a repair man to fix my air. Good thing I did, my condenser had gone out. I have air and did not wait and was not hot.

  • 3 years ago


  • Anonymous
    1 decade ago

    cool, it got fixed and the answer was also put here.. Like that....t

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