HVAC blower question [Archive] - bimmerfest

NHBimmer

10-20-2007, 04:35 PM

We just picked up our '88 535i, and the blower doesn't function unless the A/C button is depressed. All the fan speeds work fine when the A/C is on, but nothing when just the heat is on. Does anyone have any idea what might be the cause of this?
Thanks in advance!

hugh1850

11-05-2007, 01:27 PM

We just picked up our '88 535i, and the blower doesn't function unless the A/C button is depressed. All the fan speeds work fine when the A/C is on, but nothing when just the heat is on. Does anyone have any idea what might be the cause of this?
Thanks in advance!

The heat will not come out of the dash vents. Only the defrost vents and the floor. Have you opened the floor vent with slide, and then switch the fan to position 1-2-3?

jimoreno

11-11-2007, 01:52 PM

Welcome to the wonderful world of the e28 featuring TWO fans! The one right above the shifter is for the A/C and when the heat is on the one below the wipers (accesible from the engine compartment) turns on. They are never both on at the same time. On this matter as Hugh1850 stated, cold or outside air only comes out of the center vents and heats only comes out of the top and bottom vents.
Good Luck!