I have an outside A/C unit that does not do anything, I replaced the thermostat over the winter, the heat kicks on with the furnace no problem, but at the thermostat you hear the click when setting the temperature below room temperature, but nothing happens out at the outside unit. I checked the ohms at the capacitor, they went from a high # to virtually 0, could it be the run/start capacitor?

So Help me get this fixed...

Do you have 24 volts and 220 volts at the contactor? Is the capasitor swollen at the top?

I did not check the voltage there, but it had the voltage there before, so I would assume nothing has changed. There seems to be NO swelling with the Capacitor.

Is the contactor pulled in? If not try pushing it with a screw driver and see if it comes on.


http://rocky.digikey.com/weblib/Pott...42D22P1-24.jpg

Press the botton in the middle.

When you replaced the t-stat did you put a jumper from rc to rc?

I rewired it the same way it was wired, they are both electronic T-stats, nothing changed at all. I hear the click in the T-Stat when putting the temp below room temp.

I will have to test the Contactor, I was not aware of this being an issue and I will check the voltage at the terminals, which ones should I test across?

Well usually the main 220 power comes to the bottom 2 termanals, ck for 220 volts at the bottom 2 and the top two. Then the 24 volts should be two small blue wires on the left and 1 on the right side of the contactor. Chack for 24 vollts between them two.

Does your indoor blower run when the t-stat clicks for ac?

No inside blower doesn't do anything for A/C, it works great for Furnace and the heat.

OK then is sounds like it is a t-stat problem then. If neither the indoor or out work.

Take the stat off the wall and jumper between red and yellow and see if anything comes on.

Also look for that jumper between rh and rc. Make sure it is there.

OK, I guess I am very confused as it works to kick the furnace (blower) on, it also "clicks" when the unit is on cool and you set the temp below room temp?

One thing I am confused on, again I rewired it the same way (5 wire) it was before, of course it had no issues other than the heat wasn't working before. There was no "jumper" wire then, so why would I need one now?

May be you old t-stst did not have a rh and a rc just a r. rh gives the heat power and rc gives the ac power. If you have the red on rh only the ac will not recive any power inless it is jumpered to rh. Same as if you only hook the red wire to rc the furnace would not get power.

I was able to check the contactor and the button was not pushed in, however when I pushed it in the outside fan came on, so it has power to the unit, I could not get any readings at the Capacitor, so what do you think?

Did you check to see if you had a wire on rc?

No I was not able to go inside the home at the time, I will do that, however my question would come as to how there would be power to the fan/compressor and when I hit the contactor it fires the fan up. Wouldn't that indicate there is power to the system at some point, but the capacitor is not kicking the contactor on? Or maybe the contactor isn't working as it didn't push in when the signal is sent from the inside unit?

Just asking

The contactor is supposed to be pulled in by the t-stat. by you pressing it in shows that there is 220 volts going to the unit, but not 24 volts. So the problem would be at the t-stst or the indoor unit not sending the power.

OK Thanks for the information, I will check the Jumper wire and if it isn't there will replace it with one. Afterwhich I will test the system and see if it will in fact kick on or not.

BTW, thanks for all the help and explanation.