I live in a 2-story house in AZ and there are 2 Lennox (sic?) heat/AC pumps, one for each floor... it has 2 Honeywell TH8000 thermostats. Last winter there wasn't any problems but tonight it started getting cold so I turned it from cool setting to heat, I can hear relays in the TS click and it says "heat on" but nothing happens, I checked both TS and they both are doing that! I can turn it to the cool setting and turn the TS below the inside temp and the AC will come on okay so the heat pumps/AC units are running (getting power) I turned them off for awhile but no dice!
Right now the inside temp it 71 and I have them both set for 74 and nothing!
Being in the desert there isn't any 'backup' emergency heating all the heating/cooling is performed with the heat pumps only.
Any ideas?