The heat pump just stopped working yesterday. I have tried 'rebooting' the system (shut off switches breakers, wait 3 minutes then turn back on) but no luck. The fan & aux heat work fine. The programmable thermostat however seems goofy. When I try to change from eheat(aux heat) back to regular heat the entire display lights up for a minute or two. By that I mean every command word and all digits in the numerical fields are displayed. One thing I noticed is that in the ambient (room) temp display area, the letters HP are displayed. Then it goes back to a normal display, it does this for cooling as well. Could it be that I just need a new thermostat?