Air through vent's is always hot.

[theredguy]

Hi

Not long got my W202 C180 and am thoroughly pleased with it aside from 2 issues that perhapse someone could shed some light on.

The problem that fit's in this section is to do with my cabin heating. My car seems to be one of the few without climate control and no matter what setting i have my temp dials on the vent's pump out hot air (very hot at red and a bit less hot at blue) regardless of fan speed or where i have directed the air flow. Now this will be all well and good in the winter but it's not really what i wanted in the summer.

Has anyone got any ideas as to what the issue may be and how i can fix it please.

Many thanks.

 

[Dec]

A recent, similar question to yours, has a look at both pages, 1 and 2 HERE... http://forums.mercedesclub.org.uk/showthread.php?t=39484
The guy didn’t come back yet to say how he got on.

Be aware that when you turn the thumb wheel/s from hot to cold, it will take about 10 minutes for the air coming into the cabin to cool. (Check with engine and heater fan running)

Let us know how you get on.

Dec

 

[theredguy]

Nice one cheers, now where did i put that multimeter.

 

[MB TECH WARRINGTON]

Nice one cheers, now where did i put that multimeter.

possible duo valve faulty

 

[Tim Green]

Some time ago I had a E300 turbodiesel - not sure if its the same system but the controls are the same. Mine would work sometimes and othertimes would do nothing but blow hot air.
The local MB dealer first changed the thermocouple within the cabin, then the duovalves and finally the electronic module - it was the latter responsible. They tried to charge me for the whole lot but after heavy "representations" agreed to charge me for "just" the module. Seem to remember that is still cost about £300.

 

[vijilants]

By default, if you disconnect the duo valve cables they let the water through so its best to check for a pulsing voltage at the duo valves when you have the controls set to cold. If the voltage is present but the pipes into the cabin are still hot, then the valves are faulty.

 

[3ps]

I had the same problem and just fitted a used duo valve and now it works. It was a W124 and access was tight but I got it done easily enough.