'90 300D - ACC -- Poor heating in winter?

Hi,

I have a recently acquired (Oct./99) 1990 300D (North American version), and when the temperature gets cool here (-20C or about -4F) I find that my MB does not heat particularly well inside.

At highway speeds, after even 10-20 minutes of operation, I find its necessary to leave on my winter coat, have the temperature wheel set to MAX and the re-circulation engaged (in EC mode, AUTO fan speed). Its just about luke-warm inside (not as warm as I would like)

Is this normal? The engine temperature is at its normal operating temperature, no windows are open. Is this related to the mono-valves (perhaps torn)? I was considering putting a rectangular piece of cardboard in front of the radiator while the weather stays cold here to limit air flow through the radiator (I used to do this with my volkswagen all the time in winter... helped a lot).

Any help warmly accepted (brutal pun acknowledged)

Mike

I'm in the same boat with my 81 300SD. I have cardboard in front of my rad and it doesn't help that much in really cold weather. I don't need to wear a jacket but heat is like you said, just luke warm. I think its because the diesels are so efficient they simply do not produce enough waste heat. I think I'll consider a higher temp thermostat next year, maybe that'll help.

[Benzmac]

You may have one or more problems. You could have a blown fuse, you could have an auxillary water pump that has failed or a faulty mono valve assy. (You can't get just the insert for this model.)

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Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM