Hey guys,

This is my first post and I need some help; I'm not new to the "German car scene" but most of my experience is with pre 67 vw busses... I also have a 71 280sel but haven't had to do much work to it..... Anywhoo....

I just found (or it found me) a 76 300d. It runs like a top and aside from a bit of rust is a nice ride. I have been working through some electrical problems but can't figure is one out:

Was cruising around the other day and the blower (which was blowing nice warm heat) quit working... I looked for a blown fuse in the fuse box on the driver side fender but they all check out ok; However I found that if I turn on the AC, the blower will turn on and work fine, but as soon as I turn off the AC the blower will quit....?!?

So I guess I am wondering where I need to go from here, I HAVE searched and can't seem to round up an answer... Like I said, I'm new to the Merc. scene so specific advice would be great!
Thanks again for the help,
-j

It's been a while since I worked on a 115 Mercedes, but i did have a 1975 240D that I think has the same heater / AC setup. The 115 body has two fans, one for the heater and one for the AC. On my 240, there was a switch just above the accelerator pedal that was switched by a linkage on the vacuum pod that changed the vents from heat to AC. One time on my 240D, I had to manually work that switch to exercise the contacts and work the dirt out so that it would connect to the proper fan motor. It only happened once while I owned the car. Hope this helps.

Thanks for the info, I'll take a look for a manual switch above the acc pedal... I'd like to know how to remove the fan switch for the defrost/ heat, maybe there is a bad connection there? Does anyone know if this switch has a fuse that is not located in the fuse box on the fender?

Again, thank you for the help!!!

I don't remember how the wiring is arranged to the control switch on the dash, all that I know is that the same switch worked both fans. I don't have any idea where you could get a wiring diagram. Because the AC fan is working in the AC mode I would guess that the switch is OK. I never had to service the control switch, so I don't have a clue as to how to remove it.

This may be a stupid question but where is the second fan ( the one for the heat/ defrost located?) if it's not the same fan

It is in the center just under the grille that the wipers go through. I never had to service that fan, but from past posts on this forum it is very difficult to do anything with due to its location. I hope yours is OK so that you don't have to find out how to fix it. You did say that it was working in you first post. Lets hope it is a power problem and not the fan.

Do you know if it has it's own fuse? And if so where it might be located?

Thanks again for the help!
-j

Sorry, I don't know much about the fuse setup. It's been too long ago, 14 years, since I had the 115 car and I no longer have any of the manuals for it. Maybe someone else can chime in with info. As I remember there aren't too many fuses in that car compared to the newer models.
Glad to help.