Auxillary cooling fan conversion to manual switch
 

I have 560 sel 1988. It is running hot 100+ degrees in summer and stop in go traffic with A/c on. Auxillary fan did turn on but A/C was not blowing cold air. But normal running on highway is ok with nice cooling. So all the a/c swiches, relays are ok. My question is this. Is it possible to add manual switch to Auxillary fan so that I can turn on the auxillary fan whenever I want keeping automatic functions intact. I just want to add manual mode switch. I am thinking to splicing wire to Auxillary cooling fan with a manual switch lacated near the instrument panel if possible.

Simply run your cabin sw across the aux fan switch on the AC reciever/drier. That gives you a manual over-ride w/o changing any of the stock circuits.

Thank you Mr. Arthur!

You mean kind of jumping(hot wire) the drier switch? Do I have to run this manual switch wire through the battery positive terminal (I hope not). I see two switches at the drier one is red which says 20-psi and other one is at the side with two wire clip connected to that. I think the side switch is for the fan. Am I right?

You do not go to the battery or anywhere else , as you are simply using the existing circuitry..you are simply jumping the aux fan sw manually, so the circuit thinks the fan is being called for ..that way you do not need any relays of fuses. etc. You are the Switch.

To make sure you have the correct sw, simply jumper the sw and you will see the aux fan come on..then just bring two wires into the cabin to your toggle sw., while leaving the existing wires hooked up. Just tap into them.

It is the sw with the pigtail wire leads :

http://catalog.peachparts.com/ShopByVehicle.epc?q=1988-Mercedes--benz-560sel-Climate--Control&yearid=1988%40%401988&makeid=63%40%40MERCEDES%2DBENZ%40%4063%40%40MERCEDES%2DBENZ%40%40X&mod elid=6309%3AMBC%7C1547%3AED%7C10000060%40%40560SEL&catid=242213%40%40Climate+Control&subcatid=242240 @@A%2FC+Temp%2E+Switch&mode=PA

Many old Benz guys do this b/c they tow or they know there will come that time when they can stop an over-heat condition manually.
This beats the old "Turn the heater on " trick....

Thanks, Arthur! I got the point. I think i can do it. I will update you as soon as I am done.

Sahai

The aux fan is controled by the climate control. Low speed operation is controlled by a pressure switch on the receiver dryer operating one of two relays at the rear of the fues/relay box, I forger which one. Power passes through a large resistor under the brake master cyl.

High speed operation is controlled by the climate control operating the other relay and turning the fan on full. Check the resistor, the A/C pressure, and the fuses and relays.

Also, check the thermostat and replace if necessary. Change to a lower temp one.

If you're car's running 100c+ all the time, you might want to check your radiator and your fan clutch. Odds are, one or both are due for replacement.

CWW-

No its not running hot all the time just when it is hot outside, ac on and stop and go traffic. I mean nothing is wrong. I just don't like temp gage going all the way upto 100+.

Hi. Warren-

Long time no she. I can see that you respond to my post but you don't call back when I leave message for you. I still owe you coffee. You remember?

Sahai