If the air conditioner doesn't run the fan or compressor, check the AC voltage. If there are not lights showing on the thermostat, this means it's not receiving 12-volt (DC) power, so check the fuses. However, if it is your AC voltage, when you get to your destination, put in your electrical cord to shore power. Inside your RV, plug a voltmeter into an outlet and turn on the air conditioner. Wait two minutes for the compressor to start and check the voltage again. It must be over 103.5 volts for the unit to run.
If the fan runs but the compressor won't start, start by checking the voltage. One problem may be the compressor goes on and off, but it won't cool enough. It could be bad air flow, a dirty filter, dirty condenser, a leaking duct or the AC voltage. Another problem may involve the compressor not turning over. This problem may need to be fixed by a qualified mechanic because it could be the condenser. Keep in mind that poor air flow, short cycling, a dirty filter or keeping the thermostat at its lowest temperature with the fan on can involve evaporator freeze-up.
If the air conditioner is leaking, it might need to be serviced by a certified technician. The technician will check that it is tightly mounted, the roof gasket is in good shape and the condensation holes aren't plugged. Without proper tools and experience, fixing a leak can be dangerous.
