Mike in Arkansas wrote:
Let me ramble for a bit here. As I understand, you want power to the
heater available at all times when the thermostat calls for heat and
when it does you want to interrupt the power to the compressor it it
will not run until the heater goes off.

Isn't that backwards? Wouldn't you want power available to the heater
at all times except when the compressor needed to run (seldom and only
for a few seconds) Otherwise, you might have to wait until the room
came up to temperature before you could drive a nail with the compressor.

The concept would be the same, but pick up the signal from the
compressor to switch a relay rather than the thermostat. The higher
priority, lower duty cycle device should interrupt the lower priority
higher duty cycle device.