No power to heater control valve

[CaifanSC]

Frankie, this connector x612 ...does it plug into the IHKA control unit (the center console below the MID) OR the HVAC module which I think I read is in the passinger side somewhere behind the glove box(es).

My AC started being retarded so this weekend I'm checking that my heater valve is working properly and this switch.

Also, does anyone know which years of North American spec e31's came with the climate control unit with the Air Recirculation option?

thanks!

[CaifanSC]

I did this today to my IHKA control unit. My AC would work normally but on really hot days after driving and shutting the car down, sometimes the AC would blow hot when the car was restarted. New Aux pump and heater valve so this was the next thing to do. I guess I will be able to tell once days get a tad warmer during this summer. Testing today yielded ice-cold AC.

In the mean time, in case anyone is curious of what the inside of this micro switch looks like I snapped a few pix. Well...i tried, it was tricky getting decent pix with my camera phone. I ended up desoldering, cleaning with compressed air, used the Detox product suggested earlier in this thread by another member and re-soldering to the board. If you're going to fiddle with this thing be very careful with the little round piece...it acts like a leaf spring and can very easily come undone and fly across the room (making you look for it for almost 15 minutes praying to the gods that you will find it ).

It's a clever little switch this...leave it to the germans .

[CaifanSC]

WELL.....got up to 91* here today and my AC kept going hot. I'm going to check the freon pressure later today but I'm pretty sure that's fine.

Next step, IHKA computer replacement

[Frankie]

To confirm where your troubles lie:

1) Have you had your IHKA faults diagnosed?
2) Have you performed the test procedures (from the HCV plug under the hood) specified in my write-up?

[CaifanSC]

To confirm where your troubles lie:

1) Have you had your IHKA faults diagnosed?
2) Have you performed the test procedures (from the HCV plug under the hood) specified in my write-up?

Hey FRankie....not familiar with having the IHKA faults diagnosed, is that something you have to take the car to the dealer for?

Regarding your write up...yep, I followed that, got all Yes' which led to a faulty HCV, that's when I replaced it with a new bosch unit, but problem persists.

[Frankie]

....not familiar with having the IHKA faults diagnosed, is that something you have to take the car to the dealer for?

Any indy shop or dealer can do this for you, while you wait, and probably for free.

Do not proceed until this is done!

[bmw528e11]

That is a good find. I'm having an issue with my heater valve. I only get 3 volts when heater valve connected. Did swapped heater control switch assembly with a known good one, and I do have full battery voltage. Question now, Did anyone found that switch separately?