Current temperature stuck at 38°C

[MarkoPaasila]

This happened (only) when Defrost Prevention Control turned off the second time. Now it is stuck. Any idea what this indicates and what the cause could be?

I'm running mitsurunner with the native esphome api instead of mqtt. In addition, the board has:

• 2 sht30 sensors
• 1 PZEM-004t power monitor
• A relay for controlling the bottom heater. This simply monkeys the defrost prevention relay.
• esphome-mitsubishiheatpump (which controls the heatpump itself)

[MarkoPaasila]

Aha! This turns out to be what the Mitsubishi does when inside temperature (according to the indoor units own ntc) drops to 8°C or below. It refuses to produce any heat, and reports 38°C. Stupid logic. But now I know it.

The apparent solution is to prevent temperature from going below 9°C; practically to maintain it at 10°C. A lower temperature would have saved quite some energy...

[kestopuu]

Good to know. I guess that Mitsubishi is afraid that there is no much heat energy for defrosting if room temperature is too cold and it stops heating to avoid frosting.