Made a trip to VT this weekend and finally had the failing compressor on the front AC completely give up the ghost. Troubleshooting since late last summer had me considering the possibility that the house main breaker and AC breaker were weak. After replacing those I had more success running the front unit for longer, but during a trip to FL in December it had tripped again. It also tripped more often during generator use than shore power.
I now believe all of those symptoms were related to the compressor having excessive friction and slowly dying. I tried to see if some additional refrigerant might make compressor startup sound less awful and I swapped back to the original capacitor as I had changed that before I figured out the unit had leaked all the refrigerant out. Neither showed any improvement. Compressor still seemed reticent to start and even let some smoke out of one input terminal even though it did start moving.
Some history/background: I bought the RV in late 2018 with two 2015 vintage rooftop Dometic Brisk Air II ACs. Someone had never configured the jumpers on the front/rear, master/slave controllers so I'm not sure these two AC's ever worked right.
The front one was always less-cool than the rear, and may not have worked through early 2019. I found a rubbed-through copper line where two lines were touching and attempted to just solder the hole up without cutting/reworking tubing. That worked for I think 3 years, until 2022 when I then cut and replaced a section of line with two unions because it had leaked again. Each time I refilled with R410a and thought I was all set. I now wonder if those ambient air/humidity exposures and loss of oil are what has now killed the compressor.
A replacement 15k BTU heat pump / AC unit is about $1500. I hunted for a compressor and was not able to find the same PN cheaper than about $480. Compressor replacement would leave me with 3 risks:
1.) Debris from the current compressor failure is likely very hard to clean out of the multi-pass evaporator/condenser cores
2.) I worry the reversing heat-pump valve could have ingested garbage and now possible be flaky. Some suspicious noises and weird operating modes while troubleshooting the compressor....
3.) Any other portion of the system or housing could still fail - corrosion on evap core / condenser resulting in a leak.
So with that, I really don't want to put $500 into the ancient unit.
I also was hoping to invest the minimum I could to still have an RV until I can buy a much better condition RV. But I consider functional AC a must-have, so I'm going to repair it. I also now have again lost the dash AC, possibly due to crap clogging the expansion valve orifice valve again (something that I spent many hours during a couple weeks of 2019 to clean out), which kinda doesn't surprise me after 6 years. The 4.5 hour drive home yesterday at 90+ degrees with only the rear-most AC running was brutal. I don't want to do that again. I'll start troubleshooting the dash AC tonight, but the rooftop one is more important since I can use that driving and parked - dash is driving only.
I ordered a new Coleman Mach 10 15k btu heat pump / AC unit from Amazon. Hopefully I have better luck with the Coleman that I did with the former Dometic. It was $1016+tax. Hopefully it goes on OK, is quieter, and works longer than the Dometic it is replacing.