HELP PLEASE... I have a Lennox a/c unit... the compressor all of sudden stopped awhile ago. The thermostat display is working fine and the fan comes on when I turn it from "auto" to "fan"... but the outside unit won't come on at all. I tried turning main breaker off and on but nothing. ANY SUGGESTIONS...

At the outside unit do you have 220 volts coming into the contactor? Is the contactor pulling in? Check the 2 wires from the air handler going to the outside unit. Has a weedeater or animal chewed them? You can take a screwdriver and manually push it on the contactor. Does everything work when you do this?

Some Lennox units have a manual reset high pressure reset switch in the outside unit,remove the access panel, it is a red button that you have to push in. This switch will kick off in the event of high pressure , caused by the fan motor failing or a dirty condenser, if motor runs take a water hose to the coil and wash. Good luck, Mike