I have a Lennox heat pump. I have measured 220VAC to the bottom of the compressor contactor. However, when I turn the thermostat to cool the blower fan comes on but the outside compressor is not energized. I can manually engage the contactor and the compressor and cooling fan come on. I can't measure 24VAC on the other side of the contactor and I don't have a wiring diagram that I can use to trace it. I can measure 24VAC at other points in the outside compressor cabinet.

If anyone has a suggestion, I will appreciate the help.

Look for an open connection from the Y wire at thermostat to the indoor unit then to the outside unit to find where it stops sending 24 volts.