About a week ago, with outside temps of about 36, I was running the front heat pump when it started to sound funny. My first thought was to turn it off but I looked very closely at the display on the thermostat and saw the word "Defrost". This is the first time I'd ever seen the word Defrost on the thermostat.
I searched some of the other iRV2 forums and it seems that "under 40 degrees" is just too cold to be using a heat pump.
Mike and Mike (Michele)
2004 Alpine 34 FDDS