[Richard and Rhonda]

Jack,

Before you start tearing the coach apart looking for this wire. How does the A/C know to come on. Do you turn a knob mounted directly on the unit, or is there a wall thermostat? If you have a wall thermostat, then 120VAC definitely does not travel through the thermostat. The thermostat triggers a relay somewhere that turns on the juice to the A/C. Your black wire open is consistent with this. The white wire is used for neutral as you know, and the black for hot. Any relays or on/off mechanism is always used on the black.

If you have a thermostat, trace the wiring coming out of it.

As I have thought more about this, the black wire HAS to go through some sort of switch, because if the black wire to the compressor was hot all the time then the A/C would run all the time. Gotta find that switching circuit I think.