[Richard]

Yes R 22

You will have the Dometic air units. First thing to check is if the outside fan is actually running, The most common failure mode for the Dometic units is the condenser fan stops turning because the bushings become worn. If that is the case, there are few threads on the forum about replacement motors.

Second thing to check is look for the inside air handling unit. In it's close vicinity there will be a silver box. Inside the silver box are the wire nut connections that bring power to the unit. Check them for tightness. I highly recommend replacing those twist connectors with Alumicon connectors.

Third thing is the relay that supplies power to the compressor is on the printed circuit board inside the box. That relay goes bad, but can be replaced without replacing the board.

And of course it could be low on refrigerant gas.

Hope this gets you started on diagnostics.

So for grins, how many amps does the unit pull when running?
Does it cool at all? What is the temperature of the air coming out of the ducts?
Has this unit tripped the breaker recently?
Does the inside fan blow?