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Hello,
I think one side of my heater duo valve is not functioning properly.
Have to assume only one side is working properly since when the air conditioner is on, the driver side center vent blows hot. Just had a new compressor installed. So I know that's all good
It did however cool down somewhat when I turned the temperature selector from full cold to full hot..........very odd. I would think the opposite would happen.
Are the valves closed by default until heat is demanded from the control panel?
I tried pulling the plug connector and reattaching. I can hear and feel the click. Just can't tell if one are both are moving.
I also checked the heater hoses coming out of the valve with laser temp, one is hotter than the other, the left side as facing forward.
I'm not sure how to test the OHM resistance across the coils, any instruction is appreciated.
Or in leu of all this. Is it best to just replace the valve assembly?
Regards,
Florida Girl's...... Hubby home mechanic.

 

They have been taken apart, cleaned, lubricated and reinstalled with success. I don't know if new ones are available.

 

ZERACER/Florida Girl
This part is still available by MB suppliers.
Click on the link below.....
Dennis
DTMenace

2004 mercedes-benz slk32 amg heater valve in Car & Truck Parts | eBay

 

The default position of these valves is open. They can be taken apart, cleaned and lubricated. There is a HowTo on this,I’ll look for it.

 

Thanks for the replies. I have already taken it apart and cleaned it. It really was pretty clean.

Onehundred80.......... if the valves are normally open. Do you know what the trigger is to close them?

We ran the the car for 45 minutes to test the AC last night. Stayed cold the whole trip.
This morning 30 minutes to work, AC stayed cold.
This afternoon on the way home. Cold AC for 10 minutes. Then driver side went full hot.
Turned it off 2 min. then back on still hot driver side, then a few minutes later all cold again for next 25 minutes home.
Its odd that this same scenario exists across so many different cars.

 

I assume the temperature rolling **** is set to cold ,,

 

Did this fix your problem I'm having the same issue ?

 

He was not having any issue, he was just trying to help by offering a source for a part.

If your car is "blowing hot" at times, answer these questions:

1) Does the air always blow hot?
2) If not always, how often/when does it go from hot to cold or cold to hot?
3) Is it all four vents going hot or just one side?
4) Are there any other electrical issues going on? Any instrument panel warning lights on all the time?
4A) Do any instrument panel warning lights come on when the air blows hot?

The cuase can be a bad/sticky duovalve, failing power lead to the duvalve, issue in the climate control module, failure with the A/C clutch to stay engaged or other faults.
Most of the time, this is not a hard issue to resolve, if the one chasing it understands how the system works.