on my 85 300d i am experiencing heat on drivers vent and cold on passenger floor and side vent.ive read threads on vac pods,i took glove box out and opened center flap but only cold air is coming out of there.heat is not very strong anyway,both in defrost and reg modes,but having cold air coming in doesnt help.is this a pod issue and which one,any temp fixes.i dont want to take dash off.

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95 e320,87 sdl,79 300sd

anyone have any idea about this issue

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95 e320,87 sdl,79 300sd

Maybe?

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'84 300SD sold
124.128

Try unplugging your monovalve and see if things heat up. It's located under the hood on the passenger side firewall.

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1989 300E 144K

X2, I had this problem with my SD blowing AC from one side, and heat from the other side. A quick check of the monovalve revealed a tear in the rubber. After a new one I was good as gold. YMMV

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----Adam

1985 300SD 322,000

you have a McDLT

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1972 W115 220D/8 SLS, Coffman Starter "Ümläüt"

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whats a mcldt,i recently changed monovalve,aux water pump,just now i unplugged monovalve and drove it with no change.heat is still minimal,temp gauge is saying car temp is ok,radiator hoses feel warm not hot,it is about 38 degrees outside.could thermostat not be opening enough.

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95 e320,87 sdl,79 300sd

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1972 W115 220D/8 SLS, Coffman Starter "Ümläüt"

(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination

Insufficient heat due to a thermostat problem would mean the thermostat would be opening too much, unlikely since you report the engine temp OK (meaning 80C, I hope).

Have you tried rolling the temp dial all the way up to the clickstop on the red end and trying all four (one at a time) pushbuttons in the PBU (push-button unit for the climate control)? Sometimes the PBU will develop bad contacts for one button but another will be OK. Remember, you can still get heat in the a/c modes.

If you have a new monovalve and aux pump and have unplugged the monovalve with no help, you either have a partially plugged heater core, a problem in the PBU, or a flap problem due to vacuum pod failure(s) or insufficient vacuum. In your car, the vacuum manifold is located behind the row of switches above the PBU. Once you remove the PBU and the switch panel, you can test each pod separately with a Mityvac and find the bad ones (if any). You can also test the vacuum input to the manifold to confirm that vacuum is available to run the flaps.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

if by pbu you mean the ccu,i have switched them out and both units produce same issues,i will check vacum at pods with mighty vac,any way to determine heater core flow?

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95 e320,87 sdl,79 300sd

okay i want to relate what ive done to get heat back.i always suspected monovalve was not working correctly.i changed out monovalve insert and got another used solenoid ,it made it click and movement could be seen with diaghpram,but still no heat,so i tried a new solenoid and now i have heat and full retraction of valve,before it was only partly retracting if at all..both side vents and foot wells have heat as well,i guess lack of hot air only gave minimal heat to drivers vent but none to passenger side.so make sure your solenoid around the monovalve is fully retracting the valve.

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95 e320,87 sdl,79 300sd