99 W210 Climate Control - Heat fr. pass side w/AC on.
 

'99 W210 E300D

Sometimes...not always....when the car is started up and AC is on....there will be cool AC from the drivers side and center vents....but passenger side and rear seat vents have heat coming out.

?????

Also sometimes when temp is set to 70, in the mornings when outside temp is 55-60, when the car is started it blows cold AC....when it seems a bit of heat is needed. brrrrrrrrrrr!!

?????????

Need "Tips" for diagnosis and fix.

What diagnostics to run?

thanks
Warren C.

read this first....
http://www.eclassbenz.com/node/27


...then, run the following diagnostics
http://www.eclassbenz.com/acdiag


good technical stuff here....
http://continentalimports.com/ser_index.html

I complained bitterly at the Stealership regarding your second problem on our 99 wagon. I only used the stealer as the car was under Starmark coverage.

I was told this was how the car functioned, despite my w124 that won't blow any air until warm air is ready.

After several days of this, I gave up as they insisted it was functioning properly.
Their method of coming to this was finding another 99 on the lot, and turning it on to see what it did-pretty professional eh?

I still disagree with them, but got so frustrated I moved on.

Please let us know how this ultimately turns out.

My car is black. When it sits in the sun, the interior temperature sensor heats up, and the AC goes into full gear upon startup. It settles down pretty quickly.

Heat on the right side sounds like a duovalve problem.

Diagnostics Results
 

I read all the diagnostics info and ran the tests.

I found wildly fluctuating temperatures in the right side heater control. Seems to have no repeatable trigger.....temps just go up and down for now reason.

Could this be causded by bad duovalve.... If so which one?
I don't understand the function of the duovalves.

Also in the flap test....found no change in the right.center vent when switched back and forth.

Warren c.

Same problem is it the duovalve?
 

Thought I would revive this thread, as I am having the exact same problem as Warren C, did. Warren, if you are still on the site, did you fix this problem?

I have found references to the side vents putting out heat when they aren't supposed too, but was wondering if the rear vent is also a function of a malfunctioning duovalve.

Thanks
George

Replace the duovalve, under hood on passenger side.....fixed the problem.

Warren C.

Thanks
 

Thanks for the quick response. I'm on it!

NExt time it happens, give the passenger side of the duovalve some sharp taps with a wrench or hammer.

Thanks for the help. I took hte valve apart per parrot's great description, and thought maybe I had fixed it. But, alas, same problem, heat stil out of the passenger side. Guess I'll lay out the cash for a new duovalve.

George

Update - Repaced the valve and it all works well. Thanks again for the help.