On/Off Standard Mercedes Switch to Replace Fader - PeachParts Mercedes-Benz Forum

bolomiester · #1 09-10-2010, 11:45 AM

I have an 89 300se and I want replace the radio fader in the center console with a standard Mercedes, on/off switch to control a relay I have wired to the aux fan to give me manual control of it in high mode when it's really hot out and I'm stuck in traffic.

I currently have an auto parts store toggle switch doing the job and it works fine but it kinda sticks out like a sore thumb in the car's elegant interior.

I don't care about the graphics on the switch, as long as it fits the space, and has the on/off functionality I need. The fader is no longer used as the car has a modern CD player installed.

Can anyone point to the right switch if it exists?

Thanks.

MattBelliveau · #2 09-10-2010, 12:34 PM

I would be very interested in this, too.

tjts1 · #3 09-10-2010, 12:51 PM

I bypassed all the existing mercedes speaker wires and pulled 40' of new wire. The whole stock stereo system is history.

compu_85 · #4 09-10-2010, 01:21 PM

Is the hole a different size then the dash switches?

-J

Hit Man X · #5 09-10-2010, 10:40 PM

First, make sure you have the white mechanical fan (or the most updated one, some aftermarket updated are black). MB updated the fans over the years for cooling reasons. And verify your fan clutch works.

Also, get yourself the red thermostat switch that goes in the head... this turns the aux fan on sooner and will cut A/C off sooner if too hot. Also the 79°C thermostat to help drop some temps. I have no issues using the 79°C in the years I have been using it.

After that, be sure the A/C condenser is clean... remove the fan and be amazed at the amount of crap that collects behind the fan. Remove all bugs, rocks, etc from the condenser. Using a foaming cleaning agent to further remove the crap collected in there.

What issues are you having?

pmckechnie · #6 09-11-2010, 11:23 AM

Some, or maybe all 126 cars have a rear interior lamp switch in the center dash panel. It is a simple ON/OFF switch and it will fit the fader switch location. I have a power door lock switch made from a window switch in my 500 and it looks like it belongs there.

Paul

bolomiester · #7 09-11-2010, 03:33 PM

Quote:

Originally Posted by MattBelliveau

I would be very interested in this, too.

I bought a w126 seat heater switch on ebay yesterday, so I should know if it will fit in a few days. I decided to go with this switch as I have an electrical circuit designed by Arthur Dalton that requires a spdt switch, which the seat heater switch is.

When I'm finished this switch will leave the aux fan working the same way it did when the car left the factory, then when depressed one way it will give me high aux fan anytime the AC pressure switch activates, and will turn it off once I'm a highway speed with the pressure switch not activated. Flipping the switch the other way will manually turn the aux fan on at high speed. Helpful for when it's boiling hot out and I'm stuck in traffic.

If anybody's interested I'll be happy to post the wiring diagram for this modification.

ds190 · #8 09-14-2010, 07:04 PM

I did it simple because I only wanted to manually control high speed. I wired a rear seat light switch SPST to a wire bridged across the temp sensor on the head. No extra relay needed as it's a low amp circuit. MB put a relay in the fuse/relay box for the 12V circuit to the fans.

I would like to see the wiring diagram for your setup

Hit Man X · #9 09-15-2010, 12:32 AM

Okay and just ignore all my suggestions.

bolomiester · #10 09-15-2010, 03:23 PM

Quote:

Originally Posted by ds190

I did it simple because I only wanted to manually control high speed. I wired a rear seat light switch SPST to a wire bridged across the temp sensor on the head. No extra relay needed as it's a low amp circuit. MB put a relay in the fuse/relay box for the 12V circuit to the fans.

I would like to see the wiring diagram for your setup

You'll find my drawing here. Actually it's the drawing from the CD with my additions added. The circuit was designed by Arthur Dalton, I just made the drawing at his direction.

Unfortunately the seat heater switch for the gen 2 cars won't work. Unlike the gen 1 switch the rocker doesn't stay in the depressed position but pops back up to neutral. I'm not sure how it does its do, but it is different. I'll keep looking.

MattBelliveau · #11 09-15-2010, 03:45 PM

The rear dome light on the dashis a locking rocker (on off, no nuetral).

Not sure if it would fit the console spots, but might be worth a look.

bolomiester · #12 09-16-2010, 07:58 AM

Quote:

Originally Posted by MattBelliveau

The rear dome light on the dashis a locking rocker (on off, no nuetral).

Not sure if it would fit the console spots, but might be worth a look.

I thought about that but the circuit needs the neutral position. When it's in that position the mod has no effect and the aux fan works normally, low fan speed when activated by the AC pressure switch and high speed when activated by the engine temperature. Perfect for winter.

When switched one way the AC pressure switch activates the new relay and feeds full power to the aux fan through heavier wires directly from the car's B+. That way the aux fan runs at high speed anytime the AC pressure switch closes. Summer mode.

Flipping the switch the other way activates the relay manually and runs the aux fan at high speed directly from the B+, through the heavier wires. Stuck in traffic on a hot day, towing or running fully loaded mode.

ds190 · #13 09-21-2010, 08:10 AM

You may need to put your "summer mode" switch under the hood using any spst you like- beginning of summer flip it to on position, end of summer flip it off.

Then in the console, have the spst for your "tow/stuck in traffic mode" as manual control.

Or, get a Gen I switch used from Potomac German Auto, Frederick. MD?