Water valve control unit fault?

[xiaonan80]

Hi, my 2012 X5 E70 has suffered this symptom for a long time: when I put the car in venting mode (AC off, temperature set to 60F), it would blow hot air on both the driver and passenger sides. For example, today the outside temp is ~68F, and the car insists to give me ~120F at 60F set point. It's so hot that I have to turn on the AC to cool it down.


So I did some tests to check the water valve:


1) when the power is plugged in, both sides would blow warm to hot air when set at 60F, and very hot air when set at 84C;
2) if I unplug the power, it doesn't exactly the same thing: warm to hot at 60F setting, and very hot at 84C setting;
3) If i manually apply 12V (1A) between pin #1 and #3, and leave pin #2 floating, passenger side shows no difference, while driver side now is giving me warm air at 84F.
4) If 12V is applied between pin #1 and #2, the passenger side has no hot air at 84F.
5) The unplugged power supply measures ~10V between pin #1 and #2, and #1 and #3 all the time, despite the set temperature (60F vs 84F). Battery measures 12V, so no problem with that.


It seems to suggest that water valve is working properly if 12V is applied. However, the power supply seems to be under powered and it doesn't give any regulation...


My question is: does anyone know which unit controls and regulates the voltage to the water valves? Does it seem like I have a faulty control unit (if any)? If not, what else could be the reason?


Thanks a lot in advance!


Z

[Thaniel]

The IHKA controls the water valves. The default for teh values are "OPEN" so if no power is applied to them you get heat.

[xiaonan80]

Thank you for your reply! I would like to correct some of my statement in the original post. I did some tests with INPA and found that when water valve wire is unplugged, both side heater temperatures shot sky high (178F!!); while it's ~72F when wire is plugged back in. This is with both sides set at 60F and AC off. So there's some regulation from the water valve after all. It's just not shutting the flow completely.
Now one confusing part is, I'm not sure if the unwanted flow is due to a faulty water valve or a faulty IHKA with insufficient voltage.

Another observation from the past few days is that if I start the car after long idle (cold engine/coolant), the air coming out of vent would NOT be hot, and it would remain so for as long as the engine is running. However, if I then stop the car for a few minutes and restart the engine, hot air would come out very soon. It seems that the water valve is able to fully close and remain closed if the coolant/engine is cold when its energized, but it has trouble shutting the coolant flow if it's energized when the engine/coolant is hot. It still doesn't give me a solid conclusion if it's due to a faulty water valve or a faulty control unit... Any suggestion/advice?

Thank you very much!

Z

The IHKA controls the water valves. The default for teh values are "OPEN" so if no power is applied to them you get heat.