MR - was it working prior to the conversion?
I'm not sure if yours is the ACC type like in my '85 model but I ended up replacing the pushbutton control unit to get power through that circuit. On the '85 the power is supplied from the PBC unit through the evap temp switch (located on the a/c system "ducting" behind the glove box) and then on to the switch at the dryer. Prior to replacing my pushbutton unit I ran a fused 12 volt power switch to this circuit starting at the evap temp switch. When I wanted the compressor running I would throw this switch - worked fine until I replaced the PBC unit.