This past weekend, had the rig out, probably about 50 degrees or so at the coldest, and was running the heat pump all night long. Woke up in the morning to a racket from the AC, climbed up on the roof and saw there was ice interfering with the fan. Shut it down, let it warm up, and problem resolved. But I thought these things were supposed to have an ice sensor; if coils get too cold, it reverses back to AC for a period of time and melts it off. I did just install a Wacko silencer, so it may be related (not enough air flow), but, either way, I thought the Coleman heat pumps should have a sensor to stop this from happening?