Looking for help to fix a problem with the A/C in my 2005 545i SMG (~96K miles). The issue is related to the A/C system blowing hot and cold simultaneously!

When the system is initially turned on, all the vents blow cold air but after a few minutes, the windshield (defrost) and the bottom(legs) vents start to blow hot air while the middle vents (blowing directly to the driver's & passenger's faces) continue to blow cold air.

After a while, the defrost & leg vents really start to spew out super hot air! The middle vents still continue to blow cold air. I have fiddled with adjusting the amount of air to the defrost and leg vents to no avail.

I have had the unit checked and the refrigerant replaced but the issue still persists.

Any advice on possible diagnosis will be greatly appreciated.

Thanks.

 

Need to pull codes to see what is going on.

 

Before replacing the refrigerant, the repair shop checked all the codes. There is absolutely none. The system reports everything as normal!

 

have you checked your vent settings in iDrive?

 

Yes. The repair shop did check the settings in iDrive.

 

Blend doors are failing maybe. Have you done a test on them to see if they are working. I think there are 8 (if you replace 1 you want to replace them all; just my take and experience; I also replaced the blower motor and resistor since I had everything apart). I had to replace three on my car. Heater core or IHKA i believe it is called. Those are the three things that can create this issue if your compressor and clutch are working correctly and settings in iDrive are good.

 

Seanjordan20:

Thanks for the suggestion. I will ask my mechanic to look into the blend doors.

 

i am having this same issue it driving me crazy

 

I had this same issue. It was the blend doors. I changed all modules and replaced the blower motor and resistor since I had everything out.

 

Yes, it was the blend doors causing the problem.