I have about a 10 yr old system, and a programmable thermostat. It's a gas furnace, trane is the brand, I believe it's a 2 ton unit. Also a trane setup outside as well. My thermostat is calling for cooling and the fan in the furnace comes on but the outside unit is doing nothing. I've checked breaker in fuse box and also the one on the side of the house and all power is good. Any ideas? I think I need to check and make sure that the furnace is signaling the ac unit.

t-stat wire is broken, or contactor or compasitor may be bad

What are you talking about when you say a contactor? I know what the capacitor is, but not a contactor

Contactor is inside the electric pannal on the outdoor unit. It will have both the t-stat wires and the main power hooked to it

Open the acces panel to electrical on outside unit. You will see a contactor. Some are sealed contacts, most are open. If yours is open, take a screwdriver and manually push the contacts closed. If unit turns on, then you will have to find the break in the thermostat wiring, between furnace and outside condenser unit. Please let us know what you find. And come on back for any further questions.

http://yueqing-shi-shinaidi-electrical.tradenote.net/images/users/000/102/716/products_images/283101.jpg

Look at the 2 poles in the middle of it and see if they are pulled in.

Now when you say the electrical panel outside, are you talking about the one mounted to the house with the breaker in it, or where the wiring enters the unit?

Where the wires enter the unit.

I will do that and report back

OK, I manually pushed the contactor in and the outside unit came on. When I removed the access panel I found a booklet with the model # and such. The condenser unit is a trane model:TTB024C100A0. I have a sneaky suspicion that I have a chewed wire in my basement. Last fall when I turned the furnace on I found the tube for the psi sensor chewed, and had to replace it. So I think I know where to look...

Yep if it runs with the contactor pushed in you have a t-stat wire problem

Doesn't look like my post made it... pushed contacts together and it runs. I had a slight mouse problem last fall when it cooled off. I had to replace the hose for the psi sensor in the furnace last fall. So I think that I am going to need to look in the basement for some chewed wiring.

OK, so I answered twice... now with the tstat commanding ac on according to the display, and its not on, it is definitely a wiring issue between the furnace and condenser unit, right?

Yep, you got it, now all you have to do is some searching. Lol sometimes that ends up being the hardest part

Tell me about it... just sucks listening to my "better" half whine about how its 80 inside and the air is on... lol. Ill check in in a little while and tell what I found

I really appreciate the help guys!

OK good luck, I will be back on in a hr or so

No problem, please let us know how you make out. (with the ac, not the better half, lol). I've learned to tune out the whining by just drinking more beer.

Man I totally agree, for that's what I also do. Drinking beer just adds to my selective hearing... lol

You find the broken wire yet? Please let us know how things turn out.