| Originally posted by frank3@Jan 5 2005, 06:59 PM |
I hear ya...even though both temp knobs turned to red all the way, check the wheel below (above?) the middle heat vents and make sure that that is ALSO turned to the red.
it might be two problems. One
the heater valve on the engine compartment got stuck, clogged or simple died. get one on ebay replace it.
The other possibility.
Depending if you have the manual or electronic ac, there are several electric motor to open and close flaps inside the heater box, i know this because i use to have this issues and so i took the dashboard out and cleaned and lubricated all moving parts and electrical plugs...
For the manual ac control, bmw uses 3 servo motors, as they are called. one to close the blower housing, this motor is on the inside, but it closes the flaps outside the blower ousing to prevent things going into the blower when not in use.
the other 2 are responsible for directional, they direct where the flow goes inside the cabin, up down, chest.. etc.
I don't think the motors are shot, since they are very strong. would recommend unclipping them from the heater box, and moving the dials and see if they turn
just open the bottom panels on the dashboard and look for little round metal thing with 2 wires on it. the motors are held in there by clips.
try different settings and see if the turn, then try to turn the axle the motor is suppose to move and see if its free.
On the electronic ac, there are 5 motors. just follow the same procedure.
But as experience, this servo motors are very hard to fail, and so the flap inside the heater box. when i took the dashboard out on my car, all flaps where very free to move and the motors moved fine.
What does happens on this bmw's as they get old is that the electrical plugs create resistance because of rust., humidity.
since many temperature sensors and servo motors work on resistance to inform temperature or position, the ac control unit gets wrong readings.
yes it sounds complicated, but is not.. just take you time under there.
Remember that on this car, resistance is used to inform the computer a temperature value or position, this applies for sensors on the ac system. to sensors on the engine, the only difference on the engine is that the air mass sensor uses a thin heated wire to inform mass based on how much current the system draws in order to maintain that same temperature as air goes by.
Many problem with this cars is not the control unit, normally is it rusted of malfunctioning wire plugs, so just taking them out and replugging helps. and also sensors that fail.
hope this helps.