I have a 1977 300D with Climate Control. AC works great, but I have no heat. I have all of the MB technical manuals and Haynes, but no help in any. Before I start working on this problem,,,,anyone with any advice.

Howdy neighbor,

First check your antifreeze level, then that your electric pump is working, then your electric monoflow valve.

Myself, I've had to replace the inards of one of my monoflow valves, no big deal. I think the part was something around $30 at *Intercar MB* in Hampton Twp. on Rt.206 . The dealer is good for a quick fix, but *Fastlane* on this site beats there prices by a good 15 - 20% , And the parts show up very quick!

BTW, I'm in Hampton Twp. I eyeball all the MB's I see around here and must seen you at one time or another. Small world, huh?

~George~

If yours has a climate control servo
like my '79 300D has, then it may be this that needs to be changed.
Start by checking if that pump works.
Then look for leaks at the servo
(cylinder shaped at passenger side front fender)
Then go to partsshop!!
Good Luck

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD

George, where exactly is Hampton. I know where East Hampton is. I am at Mcguire AFB. I drive down Rt. 537, crossing over 206, all the time heading out towards the Mt. Holly area. Are you familar with H&H Motors on Woodlane road in Mt. Holly? My car is gold/champane with tinted rear windows.

__________________
1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

The servo type climate controls do not have the simple to repair monovalve like the latest models.

One thing that you should not overlook in a car of this age is blockage within the heater core. To check/correct this connect a water hose directly to the heater core in the reverse direction. If it flows okay, then you can eliminate that as a possible problem. If it doesn't, flowing the garden hose in the reverse direction will usually blow out the blockage.

Good luck,

Hi Rick,

I'm at the northern end of Rt. 206, way up in Sussex county. I don't get as far south as where you are, but hopefully we'll all see each other at the meeting that is being planned for next month.

~George~

Thanks for the quick feedback. Correct, 1977 model does not have the monovalve. Heater core flows freely.

Any easy way to check the servo? or the pump?

jcd,

If I can remember to get it when I'm home, I have a newsletter that was put out by IMPCO about ten years ago. It has very good troubleshooting information for both type 123 climate control systems. I don't have a scanner, or digital camera, but I could copy it and mail it to you.

Wait, maybe I can use a scanner we have here in the office.

My biggest problem will be remembering to get it when I'm at home. I will be incredibly buisy for the remainder of September.

I'll do my best to remember,

I have diagnosed the problem with heat on the 300D, 1977, a little further. A cool night in Jersey helped.

It appears that I am not getting any input/output to the heater core. With the heat off, all hoses/lines are cool to the touch. With the heater on, all hoses are hot except for the two input lines to the heater core (I think) and the output line from the heater core. Also the return line, small hose with a small metal line, that is off of the input line is hot as well.

I spoke with my father, previous owner, and he doubts that the heater core is the problem, as in May when he still owned the car, the heater worked like a blast furnace. At that time the AC did not. He took it to a repair guy who fixed the AC, but since then the heater has not worked. We have since followed up with the "mechanic" and he can't remember what he did. ( our guess is because he did something he shouldn't have)

JCD

JCD,

Did you get my email? I have photocopied the troubleshooting information I mentioned earlier. I can mail it, but it would be more convenient to FAX it if you have a fax number. Let me know if I need to go ahead and drop it in the mail.

Have a great day,

Larry,

Sent you an e-mail with my fax number at the office. I'll pick it up monday and work on the heater next weekend. Today is focused on finding a leaky hose in the locking system.

Thanks again,

Jim

Larry,

I received the technical info you faxed. It will be of great help.

Thanks so much,

JCD