240D fan switch stiff - PeachParts Mercedes-Benz Forum

bgkast · #1 12-28-2006, 02:56 PM

My 240's fan switch (manual heater controls

) has been stiff since I bought the car. Today it was so stiff that I could not turn it to get the windshield defrosted. I would like to try lubing it before I replace it, but don't know what to use to lubricate such a switch. Any suggestions? Thanks

rrgrassi · #2 12-28-2006, 03:00 PM

Does the switch have any cables attached to it?

I have the CCU, but my old truck has cables for flap moves like hot/cold and fresh/recirculate air. I use speedometer cable lube on those.

Can the switch be removed? If so clean and relube with the white lithium grease.

bgkast · #3 12-28-2006, 03:03 PM

I believe it is just an electrical switch. I'll pull it and take a look

rrgrassi · #4 12-28-2006, 03:05 PM

You could try some "tuner cleaner" the Radio Shack may still carry. That stuff works pretty good.

bgkast · #5 12-28-2006, 03:21 PM

Anybody know how to get this snap ring off? It is in a grove so you can't just pry it off the side.

The engineers did not want this thing coming apart. This snap ring was under a nut that threads on the switch (which I thought was holding the switch in) and a beauty cup that makes the knob look better.

Anybody know of a good spray lube?

pj67coll · #6 12-28-2006, 03:30 PM

The fan switch is an electrical switch but it has a bowden cable attached to it that goes from the left hand side of the switch behind the blower motor (between the blower and the firewall) and then up to the right to the fresh air flap on the front of the evaporator housing behind the glove box. It is likely that the bowden cable is the reason for the stiffness. I have the same problem. At present my entire center console is out and I'm trying to figure out how to fix the issue. My fan switch turns fine as long as the bowden cable is not connected. When it's connected you cant turn it at all. In fact I destroyed three knobs in the process of trying to turn it.

As far as removing it. It's simple enough. You simply undo the large flat washer on the front of the mounting bracket and then slide the entire switch slightly to the right if I remember correctly and you can then push it backwards and out of the mouning bracket.

UPDATE. Sorry I just had another look at your picture. Your setup is totally different than mine. I have no snap ring at all. So I cant comment on that. But I do think you should remove the faceplate first before you do anymore with that.

- Peter.

bgkast · #7 12-28-2006, 03:53 PM

Feeling around back there I did not feel any cable exiting the back of the switch. This car seems to have come with out factory AC so that could be the diffrence. How does the faceplate come off?

Stevo · #8 12-28-2006, 04:19 PM

Quote:

Originally Posted by bgkast

Feeling around back there I did not feel any cable exiting the back of the switch. This car seems to have come with out factory AC so that could be the diffrence. How does the faceplate come off?

That switch is a bugger to replace, at least it was for me. You just have too start pulling things off, knobs, face plate, its all pretty streight forward till you get to actually getting the switch out from behind the bracket

bgkast · #9 12-28-2006, 07:03 PM

Yep, that's about where I got. I just put it back together for now. I'll try some tuner cleaner as a band-aid for now.

Stevo · #10 12-28-2006, 08:43 PM

Well I might as well admit the shameful thing I did in a fit of total frustration. I CHOPPED the bracket in half and made some aluminum "splints" to put it back together. In defence of this shameful loss of cool, some other hack had already tried to get in there and had already broken one side. Maybe someone else knows how to do it.

You better just jump in there cause life without that switch might get uncomfortable, its 28 degrees up here

JimmyL · #11 12-28-2006, 08:52 PM

Isn't if funny. You sig says yours is a '79 240D. Your knob is totally different from my '80 240D. And my '80 240D is totally different from my '81 240D. hmmmmmm.......
You might look up Dave Morrison's evap removal thread, and see if it goes into how to remove your switch. It will at least show a pic of that area before/after removal/disassembly.

pj67coll · #12 12-28-2006, 10:13 PM

Here's a link to my thread with a similar problem. DMorrison helped me out a lot and there are a couple of good posts by him in the thread, as well as a link to his complete evap and heater/blower removal thread...

240D Litany of Woe!

- Peter.

Stevo · #13 12-28-2006, 10:20 PM

Quote:

Originally Posted by JimmyL

Isn't if funny. You sig says yours is a '79 240D. Your knob is totally different from my '80 240D. And my '80 240D is totally different from my '81 240D. hmmmmmm.......
You might look up Dave Morrison's evap removal thread, and see if it goes into how to remove your switch. It will at least show a pic of that area before/after removal/disassembly.

Isnt the fan switch the same. In the middle between the heat control for either side?

dmorrison · #14 12-29-2006, 02:32 AM

OK a couple of things first.
IF the car is a US car WITH an AC then go to the link below for information. If it does have an AC then the fan switch is tied to a bowden cable and the cable goes from the switch to the drivers side of the heater/evap box, then under the box to the "main air flap" lever shown in picture # 101. that picture is of a US 240D with AC.

http://www.peachparts.com/Wikka/W123Evaporator

Supposition #2. Your car is a non AC equipped car.

If so then the car setup is a bit different. Your fan switch still has the bowden cable. It still goes to the left of the heater box. But connects to a lever at the rear of the heater box. I assume that this is the main air flap located on the non AC model, I have not worked on a non AC model. The diagrams below are from the Mercedes W123 parts Manual dated 9/80 So it should cover your car.

It is possible to disconnect the bowden cable right near the switch. You should be able to see the separation point. I would suggest disconnecting the bowden cable from the switch to try and figure out which unit is giving you the problem. You can disconnect the bowden cable at the rear of the heater box. This will require removing the drivers side lower panel. You should then be able to get to the attachment point. If you don't have room for your hand and a screwdriver, this route may not be doable. Try to isolate the bowden cable from the switch. Then you can figure out which one is the problem. The 3rd possible problem could be the flap in the heater box. I would try the switch and bowden cable first.

The lock washer used on your switch.
Your setup should use a split/lock washer and a large nut to hold the switch on. Item number 186 in the diagram below showing the switch and heat controls. The washer shown should unscrew, just like a nut.

To remove the heater control panel you must remove all 3 knobs, nuts and washers from the controls. The panel then slips out off the switches. More than likely the U shaped plastic switch support is cracked. Item number 17 in the pictures below. As you install the center console, positioning is very important. The center console must be far enough forward so that when you tighten the AC or Heat control nuts (your actually pulling on the bracket ,#17) if you tighten to much, you can crack the bracket. So be careful after you repair the bracket, if you have to, not to over tighten the switch nuts. The Service Manual does cover positioning the center console and heater box for this reason. Most of the positioning is the heater box.

The black plastic bracket holding the heater controls is either riveted to the heater box or they are special nuts that hold the bracket on ( not sure which ). The colored picture is a closeup of one of them. It also shows how I wired and epoxied the broken bracket.

Dave

JimmyL · #15 12-29-2006, 10:27 AM

Quote:

Originally Posted by Stevo

Isnt the fan switch the same. In the middle between the heat control for either side?

Sorry about not being clear. The knob/switch is in the same place, just has different "graphics". Symbols look different I think is what I'm trying to say.