I have a 2019 3120RL, the rear thermostat has separate modes for heat pump and furnace. The furnace will only work if the furnace mode is selected. So mine does not switch. If the temp drops too low (like overnight) while set to heat pump mode, it will blow cold air.
__________________
2019 20th Anniversary Edition 3120RL
2019 3500 Silverado HC, SWR, Duramax
B&W 20K for GM OEM Puck
|