On my fathers 1979 300SD the climate control function (that little wheel on consol) is turning but not regualting the temp. Also not blowing heat only cold air. Any and all help would be appreciated.

__________________
"Damn the torpedos, four bells full speed ahead"
-Admiral Farragut




-1987 300E Smoke Silver
-1997 S320 Black on Black
-Soon To be E55 AMG
-27 foot Grady White Offshore Sportfish.

There have been a lot of non-heat discussions lately. Try a search on "heat" and "monovalve" to see if these start. If it's the monovalve, it sounds like a low $$ low-tech instant remedy.

BCingU, Jim

The '79 300SD does not have a monovalve, that started in '81. Check the auxiliary heating water pump, which is next to the climate control servo. The servo is mounted near the passenger side firewall. The water pump has two heater hoses going into the servo(the thing with all the vacuum lines going into it). Unhook the two wire connection from the aux. water pump and hook it up to the battery directly to see if it is working. If it is not working it will not pump hot coolant through the heating system. With the car cool and the pump hooked up directly to the battery, undo the reservoir lid, start the car,run the defrost, and see if the coolant level drops. This could also be the problem, no coolant in heating system. The pump is around 90-100 dollars, and I do not think it is repairable. If it is I hope someone will discuss that.

[Edited by patsy on 12-27-2000 at 11:15 AM]

Alex,

It could also be the potentiometer in the switch panel for the selector wheel or the ACC amplifier. If the servo is faulty, you'll not have any heat coming out at all. But I'd check the aux water pump first as patsy said.

__________________
Regards,
Aaron

Its blowing air very well. The only proplem is that the air that it is blowing is not warm. The ervo is 2 years old so servo failure is not likely.

__________________
"Damn the torpedos, four bells full speed ahead"
-Admiral Farragut




-1987 300E Smoke Silver
-1997 S320 Black on Black
-Soon To be E55 AMG
-27 foot Grady White Offshore Sportfish.

Alex,

You never know. Servo failure is indeed possible. Rebuilt units do have a somewhat high rate of failure. I had one last exactly two years in my 300SD. I replaced it again last spring. Let's hope this one doesn't go either!

__________________
Regards,
Aaron

I have a 1980 SD that has not been producing much heat lately also. After reading Patsy's post this wekend I fiddled with the pump a little.

I connected the pump to the battery and heard it run. I thought - Oh well, there must be some other problem. I then proceded to adjust the throttle linkage. After adjusting I started the car and took it for a test drive.

As I was driving the car and putting the transmission through it's paces I noticed - HEAT! The connector must not have been making very good contact. When I disconnected, then reconnected it, contact must have been reestablished.

Oh by the way, the old girl drives nicer with the throttle linkage adjusted. Now all I need to do is get the idle speed slowed down a touch.

Doug

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1980 Mercedes 300 SD, 215,000miles
2001 F-350 Powerstroke turbodiesel, Crewcab, 4x4, 81,000 miles
1993 Chevy Suburban, 185,000 miles