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Dado 540
10-07-2008, 02:11 PM
OK this is really messed up. The car is 1998 540i E39.

So when i select air flow to the feet it blows heat. very hot heat that i can not control.

When i select air flow throught the dash blows hot in summer, now that its cold it blows cold unless the car is in motion and that's when heat starts to come out.

If i do turn the air conditioning on, the cool air comes out only throught the dash vents, however heat still comes out of the floor vents.

So i was told this may be Heater Control Valve issues. Has anyone had any problems like this?

MLue1
10-07-2008, 04:15 PM
OK this is really messed up. The car is 1998 540i E39.

So when i select air flow to the feet it blows heat. very hot heat that i can not control.

When i select air flow throught the dash blows hot in summer, now that its cold it blows cold unless the car is in motion and that's when heat starts to come out.

If i do turn the air conditioning on, the cool air comes out only throught the dash vents, however heat still comes out of the floor vents.

So i was told this may be Heater Control Valve issues. Has anyone had any problems like this?Does the temp control for left and right work at all? Can you control the fan speed? if not it may be your FSU, if you can then maybe one of the flapers in the dash is not working.

Dado 540
10-07-2008, 07:13 PM
Regardless of what temperature i set it still blows hot as if it was on the max heat, and thats for driver and passenger side.

As for the fan i can control the fan speed.

MLue1
10-07-2008, 08:08 PM
Regardless of what temperature i set it still blows hot as if it was on the max heat, and thats for driver and passenger side.

As for the fan I can control the fan speed.Dado, according to my Bentley Manual the Heating and AC systen is quite involved. "The heart of it is the central console mounted panel. The system is equipped with stepper motors (4 motors for '97 models and 6 motors for '98 on) that control air distribution flaps. The motors are controlled by the IHKA Control module via the M-Bus. All of the motor processors receive the same signal but only the addressed motor will respond and move to the desired position. There is a NOTE: If the control module is replaced it must be coded using electronic service tools (DISplus, MoDiC, GT1 or equivalent)".

The only thing I ca offer at this point is if the flappers are not moving to the proper positions to control the air distribution then you may have to get a shop to take a look at this. Did you have any electrical problems before this, that may have reset the control module? The fan speed control works via a stepper motor that is NOT on the M-Bus, that is why it is still working.

Dado 540
10-07-2008, 11:42 PM
i have had some front end damage and at that time the control module might have been reset.

If i hook up the car to the scanner, would it tell me whats wrong?

MLue1
10-08-2008, 12:12 PM
i have had some front end damage and at that time the control module might have been reset.

If i hook up the car to the scanner, would it tell me whats wrong?Sorry I don't know.