Question on BMW 3-Series E36 Valve Cleaning

Hello!
I have 2 problems on my E36 318is 97' with Automatic Dual Zone Clima.

1 When I set hot air coming from the legs, the air from the passenger side is not hot. Is just warm to cold I would say...The driver side is working fine.

2 The passenger temperature at the climate panel, does not make any change to the temperature of the air coming out off the passenger 's side. All the vents have the same air temperature coming out, which is the driver 's side temperature. The passenger 's side adjustment doesn 't do anything...

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This post was auto-generated based upon a question asked on our tech article page here:

[Nick at Pelican Parts]

Is it the passenger side vent or a center vent? This could be a mode door issue. Can you check the vehicle for fault codes?

- Nick

[Manolito]

There are many things that can go wrong with a dual zone climate control system. That is probably why BMW abandoned that design in later 3-series versions.

This car has two separate water valves in the engine compartment. You should be able to tell if water is moving through both of them by feeling them when the car is warm and the heater is running.

If I recall correctly, they are powered all the time when the key is on, and a ground signal coming from the climate control actuates the valve.

There are several failure modes. The electrical connections inside the valve can corrode away. The valve itself can corrode and get stuck. The valve can get jammed up with crumbled rubber from degrading heater hoses.

When mine was acting up, I unplugged the connector and supplied power and ground with jumpers to test it. I also checked that I was getting power and ground to both sides of the plug when the heater was on.

I ended up dismantling the valve and cleaning it and it has worked since.

I have also had to replace the capacitor on the circuit board in both my e36 climate control units, but your problem does not sound like a capacitor.