At 37 degrees heater works, but not at 57

[MarcoRiv]

Strange heater behavior... The heater doors will allow the heat to work on the passenger side, and not the drives side. The other day when it got down to 37, everything worked fine...heat from every vent, defrost, and floor. The head unit is showing proper outside temperature, so is this a faulty ambient temp sensor, or something else???? Is there a link to door operation diagram? Or tech manual diagnosis?

Thanks for any input.

 

[LARRY70GS]

Is there a link to door operation diagram? Or tech manual diagnosis?

Thanks for any input.

Sure is, in the Chassis Manual for your car. They are available on E bay, usually at very reasonable prices.