I recently installed a programmable thermostat. It worked fine for the first 3 days. I did not have it mounted during this time because I wasn't sure if it would work. After 3 days, I mounted it and it still worked for 1 day.

None of the features worked, auto or fan, heating or cooling. So I did the wire test, touching the red wire to the yellow for cooling and then to the white to test heating and this worked.

So anyway, I shut off power to the AC and the furnace. Reconnect the wires and then turn everything back on and it works. This has worked every time I tried it so far.

The system stopped working again and I tried the wire test again, this time it did NOT work, so this probably is not the thermostat.

So I shut off the power to the AC unit and furnace. Disconnect the wires to the thermostat and reconnected them, then turned everything back on and lo and behold the system is working again, for now, but for how long?

Any ideas what could be the problem?

To recap:

The problem: HVAC system stops running after varying amounts of time, anywhere from 3 days to 30 minutes.

Possible clues: shutting off the power to the AC unit and the furnace, disconnecting the wires to the thermostat and then reconnecting them has made the system work every time I tried it so far.

Any ideas on what might be the problem? I greatly appreciate any input!

I would start by defaulting Thermostat and try again, besides jumping from hot to heat and hot to cool, did you also connect the wire for blower in both test. Since you don't mention blower wire, is it being hooked up, unit freezing up.

Stratmando,

Thanks for replying. I did not test the wire for the blower. If/when the unit dies again, I will try that. What do you mean when you say to default the thermostat?

I forgot to mention that I have a heat pump. Is it possible the problem is the wires? Since the system works for a little while, it mays me wonder if there is some kind of short somewhere in the system.