Didn't want to hijack @h2ofun's recent mini-split thread, so starting a new one.
I have two Mitsubishi Mr Slim systems, one with two heads (9K, 9K) and the other with three heads (18K, 12K, 6K). The two headed system works fine, drawing around 1.5kW mid-winter. The three headed system usually draws around 2.5-3kW mid-winter, and for the past year the outdoor unit has intermittently stopped working. I usually notice this by the drop in power usage reported by the Tesla API. Last winter, it only happened a couple of times and resetting the units or breaker would get them working again. This winter it has been getting progressively worse and at times the unit needs to remain off for hours or days before starting to work again. The local Mitsubishi Diamond vendor who had been maintaining the units annually replaced the logic boards and tested the thermistor but has been unable to get it working properly even after consulting with Mitsubishi. I think they have given up as it's been two months since I last heard from them. I've been unsuccessful getting anyone else to troubleshoot as most will only work on systems they installed, and Mitsub won't help homeowners directly. So, any suggestions from the experts around on what else to consider? Would the pressure switch cause this kind of behavior and how hard is it to replace? As the unit (MXZ-4B36NA) is around 10 years old, I'm starting to consider just getting new ones installed although I hoped these would last at least twice as long.
I have two Mitsubishi Mr Slim systems, one with two heads (9K, 9K) and the other with three heads (18K, 12K, 6K). The two headed system works fine, drawing around 1.5kW mid-winter. The three headed system usually draws around 2.5-3kW mid-winter, and for the past year the outdoor unit has intermittently stopped working. I usually notice this by the drop in power usage reported by the Tesla API. Last winter, it only happened a couple of times and resetting the units or breaker would get them working again. This winter it has been getting progressively worse and at times the unit needs to remain off for hours or days before starting to work again. The local Mitsubishi Diamond vendor who had been maintaining the units annually replaced the logic boards and tested the thermistor but has been unable to get it working properly even after consulting with Mitsubishi. I think they have given up as it's been two months since I last heard from them. I've been unsuccessful getting anyone else to troubleshoot as most will only work on systems they installed, and Mitsub won't help homeowners directly. So, any suggestions from the experts around on what else to consider? Would the pressure switch cause this kind of behavior and how hard is it to replace? As the unit (MXZ-4B36NA) is around 10 years old, I'm starting to consider just getting new ones installed although I hoped these would last at least twice as long.
