Hello:
For over 5 years now, GMC / Chev vehicles factory installed block heaters have a temperature controlled block heater cords. Tell tale is a molded bulge or block just up from male end of cord. It is labelled a a temperature controlled relay that prevents power transmission through the cord when temperatures are above minus15-18C (-25-28F). Does Ford put the same temperature control on their gas motors? Driving a 2022 F350 w/ a 7.3L Gas, and would like to have the block heater functioning at -10C / -23F

 

Different block heater manufacturers operate in the same general range. When correct, you have instant heat inside the vehicle on the coldest day. If not, replace the heater unit.