Just had an interesting in flight failure. Cabin Temp Control failed which popped the Cabin Temp breaker. Tried resetting the breaker but it would just pop again after a bit. I was at altitude (28k feet) before I noticed I wasn't getting heat and it was down to 30 something degrees - outside temp was like -40 (F). I tried going to manual heat and turning cabin temp up all the way and pull out the pressurization air temp bleeds. The warmest I could get it to was 42 degrees.
So working the problem I descended to a lower altitude (asked for 8k) hoping to at least warm it a little and found that I was able to get it all the way up to 70 degrees with an oat of 20f at 14k feet. Also figured out that the cabin temp control has no effect with that breaker pulled (duh).
Looking at the manual it looks like with the heat on manual that the temp should go all the way to max. Should that apply when cabin temp fails? I noticed that the vent blower turned off as well - maybe that's the reason for the loss in heat?
