E46 vents blow hot even with temperature set low

[koukimonster69]

When I have the vents set to cool without the AC on, the vent temp is as if I have the heater on full blast.

If I turn on the AC with the temp set low, the temperature is cool but not all that cold.

With the heater set to high, the temps are high and that works normally.

Is there a valve or something that isn't working?

[MarcoZandrini]

Yes, there’s a heater control valve located on the metal inner fender of the left front wheel. It has 2 hoses and and an electrical connector. It’s open unless it’s receiving 12VDC from the automatic climate control module (IHKA in BMWspeak) in the dash. These valves can stick open due to corrosion. The valve is item #4 in the link.

https://www.realoem.com/bmw/enUS/sho...diagId=64_0822

[dworthy]

+1

The heater valve default will be open. I would see about connecting to INPA or ISIT to see if there are any trouble codes in the IHKA.

[koukimonster69]

So the valve defaults to open unless it receives 12v. If I turn the temperature all the way down on the IHKA the plug should have 12v, and when I turn the temp all the way up, the plug should have 0v?

[dworthy]

So the valve defaults to open unless it receives 12v. If I turn the temperature all the way down on the IHKA the plug should have 12v, and when I turn the temp all the way up, the plug should have 0v?

Pretty much. Now it might move a little bit, as it doesn't want to overheat the cabin, but for testing it should be as close to 0v.

[koukimonster69]

I snagged a heater control valve from the junkyard and things seem to be good now

I didn't drain the coolant but when I disconnected the 2 hoses, no coolant came out, that's not normal, is it? I don't have any overheating issues and the heater works great.

[dworthy]

As long as you had the radiator cap on, very little coolant would have came out. See with a sealed system, and the resivour having a vacuum being pulled, it's not going to release much coolant. I would see about checking the coolant after a couple of days, just to make sure of course.