a. If the air conditioner compressor or fan fails to operate, chances are it is not receiving power. Be sure the power cord is plugged in and no fuses or breakers are tripped.
b. The voltage reading should be taken at the unit power supply leads. One test should be performed when the unit is turned OFF and another with it running under load. If the voltage is not within the proper operating range, it must be corrected before trouble shooting of the unit can begin.
Check for proper AC volts at the connections at the units electronic control box.
c. If no voltage is present, the problem is in the coach wiring or breaker/fuse box. If voltage is present at the control box, proceed to verify voltage at the control box connection.