Trane unit not switching from heat pump to Furnace when weather gets cold.

Jimw606

I have a trane HP system with a gas furnace for colder temps. It switches over to gas when the HP can't keep up.
Last winter it quit switching over, and I suspect it is the outdoor thermostat.
Where can I purchase one, other than Trane or A/S?

Or if you think I am of coarse, then please advise. I am open to any suggestions.

Both units work just fine separately.

HP works on heat or cold settings on Thermostat, and the furnace will work if you manually switch to emergency setting on thermostat.

Thanks Jim

kb3ca

You probably have a "fossil fuel kit" with a bad outdoor sensor/thermostat.
Check with your local HVAC companies to see if they will sell you the parts. Also, search on-line for the part which will probably be cheaper. Google "Grainger".