Mercedes-Benz Forum banner

1 - 17 of 17 Posts

·
Registered
1992 190e 2.6
Joined
·
254 Posts
Discussion Starter #1
Back again to drink from the fountain of Benz knowledge :bowdown:

This time it's a 1992 190E 2.6

(1) Auxiliary fan runs all the time. From cold start in the morning, never stops.

Fitted a new switch on the head (runs even when the leads are off of the switch), checked to see if PO mickey moused some wiring, but to no avail.

I temporarily removed both relays in the fuse box and fan still keeps running. The only way to stop it is to disconect the wires at the fan.

What gives?

(2) Additionally, while tracing wires and such I came upon a silverish electrical box behind the battery with a rotary on/off switch. What is this? I am hoping that by turning it I will get an additional 100 more horsepower :D

(3) I have a rather hard 1 to 2 upshift. I know that the vacuum thingie on the transmission is connected properly to the intake manifold (it was off before).

So in what direction do I turn the bowden nut? If that's the only point of adjustment left.

Thank you immeasurably.
 

·
Registered
98 SLK230K AMG, 98 E55T, 89 2.5-16
Joined
·
213 Posts
the front aux fans are switched from two sources - first is the thermostatic switch on the head and second the freon pressure switch mounted on or very near the a/c receiver drier.

HTH.

regards,
 

·
Registered
1992 190e 2.6
Joined
·
254 Posts
Discussion Starter #3
Thanks for the response.

Even with the temp sender on the head, the two switches on/near the drier unplugged, both fans still roar to life with ignition switched on.
 

·
Premium Member
W-1-2-3 Go!
Joined
·
16,161 Posts
The relays may be stuck in the switched position. IIRC there are two relays. Check the little black box in front of the main fuse box, there is a 40A relay in there for the auxiliary fan relays. If memory serves, the other relay should be in the main fuse box too.
 

·
Premium Member
W-1-2-3 Go!
Joined
·
16,161 Posts
Did this happen all of a sudden or has it been like this for a while?

If it's the latter, especially if you purchased it this way, it may be sourcing power from somewhere else. Check the grounds. Last thing I would check, since you've inspected the relays and switches, is the pre-resistor on the driver side frame rail.

#2 is your MAS relay. Combination fuel pump relay and AC compressor relay IIRC. Only in the later 190E 2.6's. The "switch" is to unlock or lock it into position when installed.

#3 to soften the shifting, adjust the cable so it gets more slack. Look at the threads and adjust accordingly.
 

·
Registered
1992 190e 2.6
Joined
·
254 Posts
Discussion Starter #7
I just got the car 3 days ago so no history.

Previously, the fan will come on and go off intermittently, as if some wires are touching, from a dead cold, but this new constant run is new.

The thingie on the frame rail looked suspicious so I unbolted the two wires and the fan still comes on.

I know that PO installed one piece headlights but I don't see how this can affect the fans.

Thanks.
 

·
Registered
98 SLK230K AMG, 98 E55T, 89 2.5-16
Joined
·
213 Posts
well, that's a mystery :) how about if you removed the fuse instead? if it still runs without the fuse then most probably the harness has been modified. with both relays removed it should have no source of power so the harness is suspect, either from modification or touching wires due to cracks/brittleness. and if anything else just to confirm there are two switches on the head one for aux and another for the magnetic fan clutch. and might as well check the switch sockets - the PO might have put in a jumper wire to make the fan constant? i once did it temporarily when i had to go thru traffic and knew beforehand i had a switch going bad.

regards,
 

·
Registered
1992 190e 2.6
Joined
·
254 Posts
Discussion Starter #9
well, that's a mystery :) how about if you removed the fuse instead? if it still runs without the fuse then most probably the harness has been modified. with both relays removed it should have no source of power so the harness is suspect, either from modification or touching wires due to cracks/brittleness. and if anything else just to confirm there are two switches on the head one for aux and another for the magnetic fan clutch. and might as well check the switch sockets - the PO might have put in a jumper wire to make the fan constant? i once did it temporarily when i had to go thru traffic and knew beforehand i had a switch going bad.

regards,
It is a crime to set fire to your own car? :D

Going to the garage to work on this now and will report back.
 

·
Registered
98 SLK230K AMG, 98 E55T, 89 2.5-16
Joined
·
213 Posts
great! so now you have narrowed down the possibilities. if the fan stops after removing the relays then the cause of the problem lies upstream from the relays going to the harness and the switch. btw, IIRC a member on here once changed his thermo switch to a new one but soon found out the new switch was the culprit so don't discard that possibility as well.

regards,
 

·
Registered
1992 190e 2.6
Joined
·
254 Posts
Discussion Starter #12
great! so now you have narrowed down the possibilities. if the fan stops after removing the relays then the cause of the problem lies upstream from the relays going to the harness and the switch. btw, IIRC a member on here once changed his thermo switch to a new one but soon found out the new switch was the culprit so don't discard that possibility as well.

regards,
Thanks.

But if I remove the connectors from the switches - the two on the drier (the cylindrical AC thingie with a small window to see freon) and the one with the two pins on the cylinder head, the fan still runs.
 

·
Registered
98 SLK230K AMG, 98 E55T, 89 2.5-16
Joined
·
213 Posts
hi,

correct me if i am wrong - the thermo switch that controls the aux fan has 3 prongs, and the 2-prong switch controls the magnetic clutch fan. or at least that is what i have.
 

·
Registered
98 SLK230K AMG, 98 E55T, 89 2.5-16
Joined
·
213 Posts
oops my bad - i had thought you had a magnetic clutch fan too i realize now you have the visco clutch instead so you are only using the 2-prong switch for the aux fan. mine is a 16v and set up that way (with mag clutch). in that case i suspect the problem is with a modded or damaged harness or as mbeige suggested - bad relays. power to the aux fan only comes from the relays so either the relays are stuck or the harness/switches have some issues.

regards,
 

·
Registered
98 SLK230K AMG, 98 E55T, 89 2.5-16
Joined
·
213 Posts
New relay, issue still persists.
then you have narrowed it down to the harness and the thermoswitch. the thermoswitch triggers the relay to power the aux fan so either the switch is bad, or the wires in the harness are touching somewhere. they are the only parts that can trigger the relay..you can check this by using a multitester.
 
1 - 17 of 17 Posts
Top