I am tired of patching together my automatic climate control on my '85 300D, so I tore it out and am trying to replace it with the manual climate controls from a '90's GMC. I have two questions:

1. with the climate control unit removed, what wires control the blower motor? I assume that there is a "power in" to the Control unit, and the three or four different wires out that control the different fan speeds.

2. What wires control the A/C compressor? again, I assume one "hot" wire in and one wire out to the A/C clutch.

any help would be appreciated.

Anyone?

Don't get discouraged. This may too far out for most people to feel comfortable answering.

I've not worked on this part of a Merc before, but cars generally all have a blower motor resistor. A wiring schematic for the climate control would help a lot. Try to find one if you can.

As for the specifics of the compressor, I can only tell you that on my '77 300D, there are three wires to the compressor switch. I know... I thought it was odd, too.

I haven't dug in to the climate control issues with my car yet, so I can't offer much insight regarding specifics. Besides, our cars may be completely different in so many ways. I do have electronics knowledge, though. Like I said, try to find wiring schematics. A few of us here could help you figure it out with those, myself included.

__________________
- K.C.Adams

'77 300D Euro Delivery
OM617 turbo / 4-speed swap
404 Milanbraun Metallic / 134 Dattel MB-Tex

Current status:
* Undergoing body work

My '77 300D progress thread

I'll dig up a wiring diagram and dig into the dash. I was hoping there would be some info available before I dug into the dash. I'll keep you posted.

Hey BigBillyBoy,
I would be interested in knowing how this turns out. Please keep us posted.

--Matt

__________________
KI6CCA

Current Stable:
1987 300SDL
1980 450SEL

Out to Pasture:
1982 300D KIA (Rice Rocket vs. 123: He hit me at 80-100MPH I walked away he went to the hospital. Sounds fair to me!)
1985 300D EURO Scrapped (got more money from state than car was worth)
1979 & 1980 300SD Great Cars!

I just wish that the manual controls from a 240 were more available...that would seem to be easy enough.

Yeah, I know that feeling. I don't know how many times I've spent figuring out things on my own, but this forum has still been a fantastic time saver.

__________________
- K.C.Adams

'77 300D Euro Delivery
OM617 turbo / 4-speed swap
404 Milanbraun Metallic / 134 Dattel MB-Tex

Current status:
* Undergoing body work

My '77 300D progress thread