The inverter unit works well, but after a few minutes of running on heating at round 4 amps and 49 degrees celcius for 401a gas, the compressor suddenly ramps up speed and at 6.6 amps shuts off. Then a minute or two later the unit starts heating again and the process starts over. After a few cycles there is a 6 time flash on the indoor power indicator. What will this be? I checked the indoor thirmistor on the coil and works and activates the fan on preheat. The air temp thermistor also works. Could this be any of the outdoor thermistors?