Face blowing ducts blows only cool air, defrost / foot duct blows hot

[Stilllearning6]

The dash red/blue spinning dials are both set to red.

Dash blows only outside ambient cool air.
Defrost ducts and foot ducts blow hot correctly.

When I switch to A/C mode , all ducts blow cold air correctly.


What is happening here?
Does the spinning red/blue dial affect only the dash ducts that blow air at your face?

[asianvenom]

Try pulling the negative post on your battery for 30 minutes. I had the opposite effect as yours after my battery died, it would only blow hot air. I pulled and replaced the battery which cause the system to reset. I hope that helps.

[Qsilver7]

The dash red/blue spinning dials are both set to red.

Dash blows only outside ambient cool air.
Defrost ducts and foot ducts blow hot correctly.

When I switch to A/C mode , all ducts blow cold air correctly.


What is happening here?
Does the spinning red/blue dial affect only the dash ducts that blow air at your face?

Yes to your last question, the stratified air dial located in the center dash vent (and right side of rear vent at end of console on certain model years) only controls the dash (face) vents. It allows the driver to temper the air from these vents warmer/cooler regardless of the temp selected on the IHKA control panel. The defrost & floor vents will not be affected by the stratified air dial:

[Stilllearning6]

Thank you gentlemen for the information.
You taught me that the red/blue dials control only the vents blowing at your face, and seem to only slightly alter the temperature of the master degree setting, currently set at 90 degrees.

Since the red/blue dials are set to red and yet do not allow 90 degree hot air to pass thru the face-blowing ducts,
what is the likely list of suspect instruments?

Is the HEATER CONTROL VALVE eliminated from the suspect loop because the defrost duct and the foot ducts are at full 90 degrees hot?

Is the heater control valve in the engine bay or buried within the dash?
I worked on a Saab heater valve buried within the dash and on a Dynasty heater valve within the engine bay which were not receiving appropriate input mechanical and input vacuum signals.
Thus, both heater valves appeared to have failed.
In reality, the signal sources had not been hooked up correctly.
Bad input yielded bad output.
I suspect that the BMW heater valve is getting good signal as evidenced by defrost is hot, floor duct is hot.
Is that correct thinking?

I do not know how the spinning red/blue dials are tempering the 90 degree hot air that is streaming from both the defrost and the floor ducts.
Are you suggesting that the spinning dial is stuck on full blue and not allowing any hot air to pass thru the face blowing ducts?
If so, where is the fix?

Also, I am trying to understand the role of the AUXILIARY PUMP ; not familiar with that equipment.

Asianvenom, perhaps after the rain ceases tomorrow, I can try the battery disconnect.
What red/blue dial component will that reset?

[asianvenom]

That doesnt reset your red/blue dial, but it will reset your general module. I was scared as hell why my car only blow heats even ac is on. Replaced my battery, and problem went away.

[Stilllearning6]

Research in the E39 forum revealed that the following forum posting had the same " cool air blowing from center vents" issue.
Here is the post :

https://www.bimmerforums.com/forum/s...r-dial-related

The issue was a disconnect between the center grill red/blue dial and a part inside the dash that , I suspect, must pivot a doorway.
The OP resolved the issue by removing the glovebox for access room, disconnecting a temperature control cable, removing center grill vent unit, reattach the temperature control cable.

Anyone else experience this issue?
Next week, I will attempt to duplicate the OP trailblazing write-up.
It sounds as if this might resolve the "no hot air from center vents " issue.

Comments / guidance are very welcomed.
I pulled the dash last fall , including the center vent grill .
I forgot half of what I did.
Perhaps the fix is immediately behind center grill ; a disconnected temperature control cable ??

Update:
I just read that the center vents have an electrical wire (not a Bowden cable as I had imagined) that sends a signal deeper into the dash to modify the master temperature setting.
Can anyone shed more light on this setup?