We installed a Honeywell RTH6400 thermostat in January. We now need a/c & outside unit will not come on, inside unit runs. When we installed this we thought everything was hooked up right, but who knows. We've pulled the cover off the thermostat & we have a blue wire that is taped, should it be hooked up to something? Is this a different issue all together?

Do you have a jumper wire between rh and rc?

Metal jumper wire is connected to R & Rc.

Do you have a volt meter?

No, My father does, but not here. I just looked & the red wire is on Rc. Is this correct?

Yes as long as it has a jumper. Set the t-stat so the ac should come one. Then go outside and take the 2 screws holding the panel to the electric on the ac. Right where the power goes in. look for this contactor.

http://yueqing-shi-shinaidi-electric...ges/283101.jpg

See if the two bottons in the middle are pushed in.

Did you check the breaker to the outdoor unit?

Checking will be right back.

Rember that is 220 volts so be careful you can push those buttons with a screw driver.

Not finding where the power goes in.

We reset breaker to unit earlier & no success.

Should be on the back left or the back right of the unit closest to the house.

Already tried resetting the breaker..

Is it a the entire back of the unit?

Not sure, what brand do you have?

Lennox

Yes some lennox and trane units you have to take the entire pannel off.

Ok, will do

There is only 1 black button & it seems to be pushed in

OK if it is pushed in then your t-stat is working corectly. Your problem is with your main power. 220 volt. Is there a outside disconnect for the main power on your house?