[SOLVED] Air Blows from Defrost Vents Only - 00E708 & 009C56

[Toothbrush]

Edit: Solved the issue by changing out the AC/Heating controller with one from Ebay (~$45 + shipping), part number 64119310449. Not exactly sure where the specific issue was, but definitely something in the controller itself. All the buttons worked, ISTA didn't report any other errors and I didn't try to test each and every wire/connector.

Notes: I ended up changing the water control valve 64116910544, glad I did because the one that was in there was a cheap eBay part from a previous job (water pump, hoses, etc) and broke when I removed it. Replacement was BMW part from FCP. Also, tried changed the [dynamic pressure] stepper motor under the dash/glovebox 64119321034, which did not resolve the issue. May keep that one just in case I need it, may return it.

Extra Note: the solenoids on the heater control valve do indeed warm up and that's normal.

-------------------Original post below----------------------------------------

So, issue of my own to track down. As the title says, air only blows from the windshield / defrost vents, no matter what settings I try.

Sometimes it'll only blow warm/hot air but I can get it to blow cool/cold intermittently.

Battery Voltage = idle/driving 13.9 (lowest) and above. Battery about 1.5 yrs old (can't remember exactly)

Codes:

009C56 - Present -IHKA: Heating, third row / Circulating air as high-speed (held) / Fogging sensor / Park heat LED / Third Row / Temperature sensor footwell
00E708 - Present -
009C7A - NOT Present, but in fault history - water valve right

I checked the dynamic stepper pressure motor per the attached PDF, watched it physically move while connected / used ISTA to check / read / readdress flaps - don't seem to have any reported problem with those.

I physically checked the heater control valve to see if there was something wrong, with Engine OFF / Ignition On (engine cold) and the solenoids were very hot. Is that normal? I'm guessing no. I normally buy quality parts but cheaped on on this one [Amazon] back in Feb 2020. Hoping this is the source of my issue as it's a easy fix.

[josiahg52]

I could see them getting quite hot in operation. Once (if) energized, they are resistance in the circuit and will absolutely heat up. Not a lot of surface area to dissipate the heat, either. I imagine they would get even hotter when the engine is running and is at operating temperature.

[Toothbrush]

Update: Well, since it's such an easy change and the old part was from Amazon, I went ahead and put a new heater control valve I got from FCP (good quality part), reset errors in ISTA, cranked it up and 009C56 is the only error that came back.

I really hope I don't have to pull the dash apart to fix/replace a flap motor, especially since ISTA is reporting all flaps are operating normally and the diagnostics for those run without any issues (other than the airflow doesn't change).

Or that it's some issue with the control unit.

Wife took it to the grocery store so that'll give it a chance to set any other errors.

[Toothbrush]

Final Update: All good now. Lin Bus error from the IHKA controller [64119310449]

Hopefully, there wasn't some other issue that caused the controller to fail. But... for the first time since I've owned this vehicle, Carly health status reports "Good" (no errors, aside from TPS)