I have a 2006 Tiffin Phaeton 35DH. It has two RVP 15,000-btu heat pump/air conditioners. The rear unit is working on both heat and air as expected. The front unit will fail sometimes in the AC mode. This generally happens when the outside temperature is over 100 degrees, only one occasion less than 100 degrees .... This is not a repeatable failure. It may work for days at a time with no problem in as much as 106 degree heat. It appears that the compressor is turning off, the fan continues to run and warm air is being sent through the system. I then turn the system off. After about 30-plus/minus minutes I can turn the unit back on and cold air will generally be produced. It may continue to work properly or fail once again.
I have had an A/C technician attempt to diagnosis the problem. There was never a failure in his presence. He checked all measurable components and all were within specs. He even double checked with factory reps. Coils were not dirty and there was no icing. Return air and output air differential was 18 degrees.
This fall I had a need to use the Heat Pump. Again rear unit worked as expected. The front unit did not. On one occasion, with the set point at 72 degrees and outside temperature in the 50s the unit quit producing warm air. I assume that the compressor had turned off. This again does not happen all the time. Unit would often work well with outside temperatures in the mid 40's. During this trip, this failure repeated itself four or five times. After turning the unit off for 30 plus or minus minute's warm air would normally be produced.