W115 heater with pics

[meltedpanda]

ok . here is what you need to do . test for 12 v before and after the fuse. If that is good go to switch wires, brown is ground, with car on or running , switch on high you should see 12v

[crojack]

thanks, with the holiday coming up, I should have some more days to work on her. She's a daily driver so it's hard to dig into anything that I can't complete in a few hours or a weekend.

Do you mean the heater switch in the dash? And how do I get the bezel off to get to the switch?

[meltedpanda]

should screw off, and yes that switch, or better yet the wires to the fan if you can isolate them

[Topher39]

Something I overlooked on getting my HEATER FAN working - You have to make sure that the main, sliding AC / HV switch in the center console is switched all the way to the far right under HV - otherwise the heater blower will not come on at all. On my car this center, top, sliding main switch controls which fan is operated by the 3 position rotary switch as well as closing operating the internal/external air feed. Slide to the "AC" side and the lower squirrel cage blower works off the 3 position switch, Slide to the far right under the HV side and the heater blower will be controlled by the 3 position rotary switch. At first, I had the AC blower going and not the heater blower.

Of course you have to find out why your not getting power to the fuse on the main panel, then tackle down stream at the switches. Without power to fuse on either end, your lost. When you test make sure the car ignition is in the ON position.

If it was me, I would first access the wires under the vent grill at the edge of the hood, where you can assess the heater fan. Expose those wires and try running 12 volts right to those exposed fan leads and see if you can get that fan turning! If you get the fan working, I would be encouraged to track down any problems with wires/switches! But that would be jumping ahead!

Just my .02¢ -

[crojack]

Do you mean the slider that controls the fresh air vent? I'm pretty sure it stays so the vent in closed. Also, my AC fan doesn't work either, although the vacuum changeover thing does work.

Whats the best way to get 12 volts to those wires, run a wire form the battery?

I'll be digging into it this holiday.

Thanks and don't eat too much!

[Topher39]

The slider that controls the fresh air - located at the top of the center console, just above the temperature control, Lighter and Hazard switch (on my '69 220)

To jump the fan to see if it works (the shortest shortcut) would be to run a couple wires off the battery.

Good luck, sorry, already ate too much!

Chris

[crojack]

So, two wires off the battery and onto the male plugs on the inside of the firewall?
I'm sure I'm making this waay harder than it actually is.

I ran a wire from the positive on the battery and touched each of the make plugs and got nothing. I don't think I can get the actual wires our from under the leaf guard to try and run wires from the battery straight to the fan.

Also, with the car on and fan switch all the way on, I tested the wire loom that plugs into the firewall, got nothing but like 0.3. But I'm not sure if that is a valid test.

Still can't get the bezel off, the heater switch knob seems to be stuck on there pretty good.

[meltedpanda]

if you can get the test to the plug , look for 12v when the switch is full on and car on number 2 position. Also if you run 12V to it , remember brown is ground in MB. you have to run two wires hot and ground

[crojack]

Success!! Well, sort of. I ran a ground and a hot wire from the battery to the male plugs on the inside of the firewall and the fan came on!!!!!!!!!!!!!!!!!!

screeched a bit and than it stopped screeching and just spun and spun.


So, now I guess it's tracking down at the switch? I got the bezel part of the way off but can't figure out how to get the fresh air slider detached to pull the whole unit out?


Or I've also been told it could be the AC switch and not the heater switch, or maybe that's wrong.

At least I know the actual blower motor works!
Thanks guys!

[crojack]

I got the bezel and everything apart this morning and unplugged the wiring harness 6-point plug. Since it is all together and I can't see the wires I just tested all 6 plugs to see if anything was there. I did get a 12 volt reading out of two of the holes. So, I guess that means I'm getting 12 volts to the switch? Which would mean the switch is bad?

On another note I noticed what I thought was a broken wire, but when I turned on the lights the end of it lit up, fiber optics! So, cool!

[meltedpanda]

if you are getting 12 v to switch and the fan runs with 12 V , then your switch is most likely the culprit
and yes old timey fiber optics ..lol

[crojack]

yeah, seems like it. Don't suppose you have one sitting around do you?

[meltedpanda]

I'll look ,one never knows

[Topher39]

You could always run some new wires from the firewall and put your own switch in to be done with it.

[crojack]

That's what I was thinking, but I don't want to hack into the existing wiring harness. Is it possible to make the female plugs that MB uses for connections?
Or any ideas on how to wire it in without cutting wires?