Intermittent problem with my Coleman Mach 8 15K heat pump
My one remaining original rooftop unit is acting up. Its behavior is very puzzling. Here's what happens. If the AC has sat off for a week or so (I don't have an exact amount of time, but it is more than a day or two), the compressor and blower turn on and run for about 3-40 minutes. After that, the compressor shuts off and the blower continues to run. After 3 or 4 days, it will run again for about 30-40 minutes.
In trying to diagnose the problem, I tried short the red and yellow wires on the thermostat. According the the pin out on the thermostat, this should turn the compressor on. The first time I tried it, the compressor fired right up. I put the thermostat back and everything was fine for 30-40 minutes when the compressor quit. I tried the red wire to yellow wire trick again and I could hear the relay click, but the compressor didn't start. 3 or 4 days later, it did.
Since I can make it fail and it takes so long for it to start again, I am guessing this isn't a temperature, freeze, or pressure problem. I would think overnight would resolve any one of those issues. On the other hand, I am not so sure about the start and run capacitors. I am not sure how they fit into the equation. If one of the caps was leaking or shorted, could it take days to resolve?
I recently had foot surgery and cannot get on the roof. I have a mobile repair guy coming over next week and I am hoping to get him to diagnose the problem and repair it, rather than telling me I need to replace the unit.
Has anyone seen this problem or can anyone steer me somewhere I can get some help? Thanks in advance.
2017 Allegro Bus 45OPP, Cummins ISL 450, Allison 3000