No heat from center vents
 

I can't seem to get heat or air to come out of the two center vents in my '89 300CE. If I turn the temperature dial down towards the cold side to engage the A/C, I do get air coming out, but it stops after I turn the temperature dial back towards warm/hot. I do get air out of the two corner vents on the dash when the defrost or bi level setting is selected. Is this a vacuum problem or should I be looking for something else?

My cars don't put heat out the center by design. Not sure if all MBs are that way.

This is the way it is meant to function, only cool/cold air from the centre vents.

No problem, take care,
Acky

Yeah I suppose the "German Engineers" liked the fact that its 20degrees outside and your left hand is toasty, and your right hand is freezing!

I'm guessing that if the heat came out the center vents, it would hit the interior temperature sensor too soon, and cause erratic climate control. The sensor is directly above the center vents, and hot air rises......



-tp

To best of my "limited" knowledge a 89 300ce is basically a 124 chassis and will have the same ACC controls as my 94 e320 Wagon.

If so, with temp dial in hot range and [up & down] button depressed, heat comes out of ALL vents.

Does heat come out of floor vents where center console meets dash?

If heat is only coming out of defrost, it's in default mode. Vac controller is accessed by removing glove box. Vac is supplied through check valve mounted behind master cylinder. This vac feed line routes under heater box and battery. Line often cracks and looses vac pressure causing system to go into default.

X2

MB didn't want heat to come out of the center vents. Not in the 124 anyways. I believe it states that in the owners manual.

Center Vent Heat - correction
 

Money Pit Driver

Wife has our "money pit" on the road. So I just checked my 124 CD Repair Manual. You're right, only cooled air thru center vents. I always wanted heated air thru center vents. I guess MB doesn't care about sending warm air to rear passengers. Fortunately, my golden retriever doesn't mind.

Note to mbzman: It's the button with both solid white arrows closest to temp dial. And vac hose goes to reservoir in rf fender well before going into cabin.

The rear passengers should get some heated air through floor vents under the front seats, although I'm sure the volume isn't very high.

My W124 doesn't blow heat thru the center vents either (and confirmed in the manual as well), but the MB engineers must have changed their tune in later years. My other MB vehicles dispense heat freely through the center vents...

anthonyb wrote
"The rear passengers should get some heated air through floor vents under the front seats"

... You mean the ones covered by the squished forward floor mat? :shocked:
It's a shame they didn't route the heat thru the center drive shaft tunnel.

G-Benz wrote
"My other MB vehicles dispense heat freely through the center vents"

... Probably a mental transference when I was fixing mine and dreaming how I could modify it to push heat thru the center vents. :idea:

Lets hope mbzman's pods are ok

Not that I would ever own one, but all the American cars that I have been in direct ALL the air to the floor when you set their manual HVAC controls to the heater setting. Although you can leave them set on vent and all that hot air comes out at your face. I personally can't stand hot air blowing anywhere near my face. Both the Audi and BMW of family members work just as the Mercedes system, no heat from the center vent.

Over the years I've read many owners manuals describing getting heat in the cabin and simultaneously cool air on the face ... to keep you awake.