AC blowing warm air in the middle vents

[SMOKEY53]

In a previous car this occurred to me when the actuating flap for the heater box got stuck open.

I did a google search to see if it affected the e53 and found this link

Heater control actuator flap problem help - Bimmerfest - BMW Forums

Here is a link to the valve if you're trying to sight it

Heater Valve - E39, X5 - Turner Motorsport


That smell you're getting, e39's are notorious for it and I'm pretty sure the e53 shares the same system. It's referred to 'gym sock' smell. It comes from mildew growing inside the condensor, just a bad design. Can be quick fixed by spraying a special deoderizer through the vents - but the proper fix is to get access to the condenser and spray it directly on there. In the e39 that involved drilling a hole to get inside the box.

[upallnight]

Originally Posted by SMOKEY53

In a previous car this occurred to me when the actuating flap for the heater box got stuck open.

I did a google search to see if it affected the e53 and found this link

Heater control actuator flap problem help - Bimmerfest - BMW Forums

Here is a link to the valve if you're trying to sight it

Heater Valve - E39, X5 - Turner Motorsport


That smell you're getting, e39's are notorious for it and I'm pretty sure the e53 shares the same system. It's referred to 'gym sock' smell. It comes from mildew growing inside the condensor, just a bad design. Can be quick fixed by spraying a special deoderizer through the vents - but the proper fix is to get access to the condenser and spray it directly on there. In the e39 that involved drilling a hole to get inside the box.

Actually it mildew in the evaporator. Warm moist air is condensing on the cold evaporator coil. The condenser is located at the front of the car.

[SMOKEY53]

Originally Posted by upallnight

Actually it mildew in the evaporator. Warm moist air is condensing on the cold evaporator coil. The condenser is located at the front of the car.

Thanks. Not a HVAC expert by any means! What he said

[Qsilver7]

Originally Posted by SMOKEY53

...That smell you're getting, e39's are notorious for it and I'm pretty sure the e53 shares the same system. It's referred to 'gym sock' smell. It comes from mildew growing {"in the evaporator. Warm moist air is condensing on the cold evaporator coil"}, just a bad design. Can be quick fixed by spraying a special deoderizer through the vents - but the proper fix is to get access to the condenser and spray it directly on there. In the e39 that involved drilling a hole to get inside the box.

To help prevent the growth of bacteria...especially if you're running the AC and you're going to be pulling into a dark garage...you may want to either run an oft over-looked OBC feature...the immediate vent option (if you have the high MID or Navigation monitor)...or turn the AC off a mile or so before your final destination (if you can handle it). This will allow ambient air to pass over the evaporator coil that won't cause a build up of condensate.

The immediate VENT ON feature can only be initiated when the ignition is in position 1. You can then turn the engine off and the HVAC blower will run for up to 30 minutes, then shut off. This works great especially if it's too hot to turn the AC off a mile before reaching your final destination.[indent]The VENT & timed PARKED VENTING features are access by pressing the clock face button. The immediate VENT feature requires that the ignition be in POSITION 1 (only)...but the timed parked venting doesn't matter as long as the ignition is on...you can set-up a timed event:

1. press the clock-face button on the right side of the MID until you see VENT ON or 1TIMER2 appear in the MID's display
   • 
2. press VENT ON (for immediate venting) or either side of the 1TIMER2 button to begin setting a timed event
   • 
3. input the time you want the vent timer to start
4. press the SET button

If you have the Nav monitor...select the AUX Ventilation prompt...then follow basically the same procedure of either immediate venting or putting in a timed event: