Came home from work to find no AC. I checked the thermostat and the display was blank. After replacing the batteries and resetting the program, my AC unit never started up.

I checked: - The AC unit (Carrier) outside to see if the fans was spinning, but it was not. It does appear to move freely when I pushed/spun it. - The breaker downstairs, it was fine. Still I flipped it on-off-on. - The tech switch on the side of furnace was on, still I flipped that on-off-on. - The fan does come on, but only blows ambient temperature air. - When I set the thermostat (White-Rogers) Off, then to Cool. The cool message blinks for a while. - I moved the Y wire to the RC terminal, but nothing happens.

I just moved into this house, and AC was working fine for the past 3 months.

  • Is there power on the R and/or Rc terminal at the thermostat? If you put the fan switch in the FAN position, does the blower come on? When the thermostat is calling for cool, is there continuity between Rc and Y? Are there separate power supplies for heat and cool (i.e. is there a wired connected to R and Rc, or is there a jumper between the two and only a wire to R or Rc?
    – Tester101
    Commented Aug 27, 2014 at 1:34
  • There is a jumper from the RH to RC. RH is wired direct.
    – Shawn
    Commented Aug 27, 2014 at 1:54
  • I have not checked to see if there is power/continuity between the Y and RC terminals. I don't have a multimeter for that :$
    – Shawn
    Commented Aug 27, 2014 at 1:56
  • Are there any error codes (lights) on, on the furnace/air handler?
    – Tester101
    Commented Aug 27, 2014 at 2:10
  • 1
    Several utilities have a program that helps their collective customers save money, by remotely turning off the air conditioner every so often. Where I live in MN, Connexus Energy turns the thing off on some of the heaviest demand days, to make sure there's enough power to go around. Your home's previous owner may have signed up for something like that... the savings, while not substantial, are decent, on the order of around 15% of your summertime bills.
    – alt
    Commented Aug 27, 2014 at 11:52

2 Answers 2


Did some further sleuthing and found the capacitor on the unit is shot.

Thanks to all for the input.

  • 1
    Hi! It looks like you’ve accidentally created a couple of accounts. If you’d like to merge them (there are some advantages to doing so), the instructions are here. Welcome to the site!
    – Niall C.
    Commented Aug 28, 2014 at 1:32

Check the breaker again by replacing it with a known good one. This is assuming that you know how to disconnect power to the breaker in question!

Either buy another breaker or find one nearby that has the same amp rating (mine was the oven/ range). I had the same problem not too long ago. Breaker wasn't tripped, resetting had no effect; only replacing it with a known good allowed the unit to turn back on.

Always make sure that there is no power to the breaker before working on / around electrical equipment by checking with a good meter!!!

I read that you do not have a multimeter in the comments on your question. I suggest that you either buy one now (I do not suggest Harbor Freight for a multimeter for this job - open one up sometime and you will see why!) or it is time to call on someone who does!

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.