No heat or lack thereof

[kxmills]

I have noticed that there is cold air coming out of any of the interior dash and floor vents on the left side of my vehicle. Altoughh I rotate the temperature knob all the way to 80 degrees and back to zero there is no change in the air temperature. The air coming out the dash and floor vents on the right side is warm and it responds to variations when I rotate the ride side knob.

[shogun]

it looks like your hot water valve for the left side is stuck.
Try to bang it with a mallet, sometimes it helps.
Next : the temperature sensor is defective on that side.
Next: the potentiometer is defective to adjust the temperature

First thing you should try: disconnect the power (the plug on top of the heater valves) from the heater valves. No power = valves are (or should) be completely open). If not, valve is stuck

[632 Regal]

right, electric power is only to close the valves. they become crusty and get stuck if the system is dirty.

[kxmills]

Its an 89 535i

[Robert K]

There are small electric motors that open and close flaps in the HVAC system. When I had a similar problem, one of the motors had disengaged from the socket it was mounted in. The motor still worked, it just didn't turn the flap it was supposed to. Something to think about. The motors are located on the HVAC system behind the radio. You'd have to check the Bentley manual for exact locations.

Grace and peace,

Robert K
1991 535i