2004 330xi Heater Issue

[morganbressler]

About 6 months ago I bought a 2004 330xi. It's been a great car, but as it's been cold here lately I've been noticing what I think is a problem.

If I have the heater fan turned on full blast and the little knob near the upper vent turned to any of the red dots, the blower doesn't seem to put out much pressure. If I flip that knob to the coldest setting, regardless of what temperature the display is set at, it blows full pressure. This is only concerning the dash vents, not the foot vents or the up-arrow window vents.

So, clearly the vent is capable of pushing full pressure, but not when I have that top knob changed to the hot settings. Any suggestions?

Thank you,
Morgan

[rowdy lee]

My guess (sorry), would be... When that knob is turned, so red dots are showing, it's supposed to allow some extra, warm air to come out, right?

That it blows full force on cold seems to me to indicate that there is a valve (supposedly, 5 little motorized valves in the system), which is working for the cold air supply, but not for the warm. As it was explained to me that those outlets are for a bit of extra, whatever, it could be a more simple air flap which isn't working/diverting. IDK if that knob controls something electronically or mechanically... or both.

If it was me, I'd go to RealOEM.com and try to look at all parts in the system and get a better idea, or look into the Bentley manual. You'll want to see what parts are/do what, eventually.
IDK if a Dealer's diagnostic systems could identify the exact problem... if it can scan that system 100%.

[telijah]

This generally happens when the "location" is set to Auto. Try turning the center wheel between the center vents to the red dots, and then manually select the face zone on the control unit (as opposed to windshield and foot wells).

[morganbressler]

See, I usually do that, fermunky. The past week I started trying the auto setting, but have found I don't like it, so I went back to manual. It was then that I noticed it seems like the air isn't blowing as hard.

Why couldn't BMW have just not included that little knob? I always hated on my e36 how there's driver and passenger controls, and then this random knob that can throw off the whole thing.

I'll try your suggestion. Thank you. Thanks for the above info too, rowdy lee. I'll look at the parts schem to see what I can find. On the e36 it's just a mechanical flap - might be the same on the new car.

[telijah]

Yeah, just try:
- Center wheel to 3 red dots
- Fan speed manually set pretty high
- Zone setting manually set to face only
- Temp set to whatever you'd like.