Hi
I have a Pre-LCI E60 550i (RHD). I'm having some heating/cooling issue. The 2 vents near the driver side and half of the vent near the windshield (for defrosting) is working fine. The air gets hotter or colder depending on the knob. But all other vents are blowing ice cold air. I had spare AC control unit. I swapped it but no change.

Next, I used ISTA to grab some live data to figure out if any of the stepper motors are bad. From iDrive, I maxed out all the bars. So it's blowing air through all the vents.

Few things that I noticed
- Cold-air flap, motor position is at 0.00%
- Heat exchanger for heating system, temperature, left is reading 10°C. While the right heat exchanger is reading around 33.5°C

But I'm not sure where to go from here. What do I need to replace or check next? I uploaded pics of the live data. Can anyone please point me in the right direction.

Thanks.

 

Get the car to operating temp and have the heat on. Do a temp test on the hoses coming out of the heater valve going towards the firewall. If they are significantly different in temp then you've found your issue. If not then you know the problem is after the firewall