[rforeman]

My ac was running yesterday and blowing hot air. The fan on the condensing unit locked up. I replaced the fan and the capacitor and the thermostat to that unit went blank. You can get the unit started from outside and I took the faceplate off the thermostat and put interchanged it with the thermosatat on my second unit and it works fine. Why will the thermostat not get any power?

[wmproop]

Start looking for broken tstat wires between the furnace?airhandler... if OK check for power to furnace,, is power going to transformer is there low voltage power (24-27 volts coming out of transformer, before you do all this turn off the power at breaker box to furnace, wait a couple minutes turn back on,see if this helps power to tstat,, you didn`t say if the tstat has or needs batteries,, if so change them