Good Day All!

I attempted to turn on my heater today. Although I set the knob on the Climate Control Unit (CCU) to 80 and the button for Economy, all I got was cool air out of the center vents.

Where should I start to troubleshoot this one?

Thanks for any advice!!!

glenn

__________________
1987 300 TD - Kraut
1987 300 D - Hans

startekinfo.com
MB workshop resources on the left side
Go to the 3rd or 4th page look for 124 service info
Navigate to chapter 83 for the procedure.
It calls for a special test box but you can get by without it.

Verify fuse 7 is good first. Pull it out to be sure.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Based on your original post, it wasn't clear if you got heat out of the other vents. Did you get any heat anywhere? Also, did you get cold air blown at you through the center vents, or was there perhaps just nothing coming out of the vents?

My understanding is that the vacuum pods for the center dash vents are designed to close when the car enters a heating condition. So if you were getting heat elsewhere, it may have been operating correctly. In my car, (when set to economy and the fan on high), if I have the temperature wheel at a low temp, I can get air blown out of the center vents. If I rotate the temp dial to a higher temp (and change nothing else), I can feel the air flow disappear through those center vents.

Anyway, others with better understanding will no doubt weigh in, but perhaps it is working as designed (though not ideal if you want to ever warm your right hand by putting it close to a vent).

__________________
1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).

Thank You for the replies!

jay_bob - I will hit the site later and check its contents. :-)

Shortsguy1 - There is nothing coming from the side vents; Cool air coming from the center vents. I know I need to replace one of the vacuum pods. I had tested the controller for holding vacuum. 2 were bad but one was the pod behind the glove compartment. I replaced that one. I am not ready to tear apart the dash yet... :-)

Thank You!

glenn

__________________
1987 300 TD - Kraut
1987 300 D - Hans

Don't fear the dash removal. It really isn't that bad.

http://www.peachparts.com/shopforum/diesel-discussion/358955-w124-c-leaks-evap-replacement-more.html

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech