W140 Rear Duovalve Rebuild DIY...

[pcmaher]

W140 Rear Duovalve Rebuild DIY...

http://v12uberalles.com/Rear_AC_System.htm

This was a fun project. Not an economical use of time, but fun.

[lee polowczuk]

It's been a long time since I have seen a car with that much corrosion...Does Chicago still use salt on its roads? I thought at first you lived by the ocean..

Nice job on the rebuild... I keep a spare monovalve on the shelf for our 124's

[pcmaher]

Thanks for the compliment Lee. The car body and under carraige is free of rust. It's these little components that seem to suffer. And yes, we may as well live IN the ocean here in Chicago, because the streets are always salted in the winter. It really causes havoc with our metal parts.

[TERRY GATES]

Nice job i noticed that their is a similiar valve on the heater control for left and right zone on my w140 for the front compartment. I took it apart and found a bad unit if i remember it was the right side giving off heat and the left was not . anyway same coil problem since this is a florida ride they never turn on the heat so will look into that repair thanks for a great article tag

[wmercer]

Nice explanation on the Rear A/C. Better than Alldata, which does not specifically call out a "rear duovalve", until you hunt around a bit and interpolate. I have a W140 1993 600SEL. The right rear a/c outlet runs hot all the time. I checked both rear heater core temp sensors and rear a/c control module. Left rear a/c outlets seems to work ok hot and cold. Front a/c and heater controls seem ok. DTC indicates open or shorted right duovalve. Are there two duovalve assemblies on these cars? I can locate my duovalve at the left front engine compartment, next to the hydraulic ride system reservoir. Does this car have duo valve control both the front and rear A/C heater coolant return flows? Have relooked your diagrams and they helped a lot in showing the "rear duovalve".
Thanks

[syljua]

Well, the article is about "rear" duovalve located outside the passanger
footwell...

As a reference, have a look at the parts drawings here;
http://tinyurl.com/87jgp
you may have to scroll down the page to see.

A new read duo costs;
http://tinyurl.com/bebv8

br,
syljua

[wmercer]

Well,
thank you.

[haasman]

pcmaher

Great job. Very nice to see such carefully documented steps. Although I don't own a 140 series car, through your instructions I could see easily how to do the repair.

I really like your use of the aluminum bead blasting. Cleaned up well.

Submit it to the DIY section.

Haasman

[whunter]

Originally Posted by syljua

A new read duo costs;
http://tinyurl.com/bebv8

br,
syljua

English is easier for me to read.
On line website translation.
http://www.worldlingo.com/en/websites/url_translator.html

Availability

Please you add the appropriate part number beginning with one Letter and without blanks, z.B. A0003600064.
If of you desired spare part is available, contacts you please the nearest Mercedes Benz contracting party for your order.

A1408300784
VALVE
EUR 220.40
You know this spare part with your nearest Mercedes Benz Selling partners order.
The indicated price contains the legal Value added tax.
Please you consider: for all parts we hold ourselves Intermediate sale and price adjustments forwards.

[pcmaher]

Thanks for your kind words everyone. wmercer, yes, as you probably guessed by now, there are two duovalve assemblies. The one that controls the rear unit is the assembly that is behind the front right wheel. Your problem is exactly what I was experiencing...the right rear vent was blowing hot.