DIY 94 E320 Auxilliary Fan Mod Definitive Answers
 

Got a 94 E320 and interested in doing the auxiliary fan turn-on mod myself.

Read lots of old posts, looked at Jim's Cool Harness, and am unsure whether or not it can or should be done on 94 E320s.

Most of the posts I'm finding were done during the discovery process which confuses me.

Can it be done on 94 E320s? Is the sensor I'm pointing to the right one? And have there been any legacy or long term problems caused by implementation.

Anybody with a 94 E320 out there done it? All I do is solder in a 1.1 ohm resistor in the CT sensor?

http://i931.photobucket.com/albums/a...x/DSCN4985.jpg

Yup, that's the sensor and yes it does work.

I have this done to my 300CE.

What does the mod do to the fan operation?

It makes them come onto high sooner.

It will also make the automatic climate control start trying to heat sooner when the engine is cold.

-J

As has been said, the mod tricks the PBU into thinking the coolant is hotter than it really is. This causes the aux fan to come on at a lower coolant temp but also causes the cabin heater to blow not quite warm air while the engine gets to operating temp.

Sixto
87 300D

It also makes the fan stay on until a cooler temp is reached to turn it off. So once it is on it usually stays on. That is the main reason that I stopped using the resistor. It just sucks so much electricity, almost like you would want to use a larger amp alternator so the rest of your power requirements are met.

You can try it just by wrapping the resistor ends around the contacts, no need for soldering until you run it for a while and like it.

is this the front fan that turns on at a certain temp? I want this wired to turn on or stay after the car is shut off. Mine does not come on while running the car but after it sits and I turn the key on it is on. It would be nice to keep cooling after car is off.

75 450SL

don't have to solder.... just wrap..

it's the "arthur dalton" fix

The engine generates heat during operation. No operation, no additional heat. The water/coolant helps dissipate the engine heat as the heat transfers from the engine to the water and the water circulates. The water goes into the radiator where the heat from the water is transferred and the water is cooled (sometimes with the aid of the aux fan).

When the engine is shut off the water stops circulating so the water increases in temperature and continues to increase until it matches the engine temp and then they both decrease in temperature together to reach ambient temperature.

The aux fan comes on at a certain water temperature among other reasons. So it comes on when the engine is started after it has recently been allowed to increase in temperature due to water/coolant not circulating.

All this to say that you will need an electric water pump to solve your perceived issue. Our cars were engineered so that we do not need to do anything like that.

in newer cars the electric fan continues to run until it cool down, I want that.

Why would you want to waste power and the life of your fan by having it run while your car is off? The engine can have buckets of heat while its off, and still be fine, because there is no load. If you really wanted to be anal, you could leave the key to ACC2 (or the one right before start), and if the engine is hot enough the aux fan will operate, and then you can run the heater on full blast to take all of excess heat....so your engine is nice and cold when you go to restart it.

The fan will shut off when cool, no wasting fan life or battery. I have 75 with the cats under the hood, while driving the fan does not come on, all the fresh air moving thru it keeps it cool. After I stop and shut it down the heat builds up under the hood with no way to move it out, I then have the vapor lock issue of restarting. It runs fine after it gets going and the aux fan shuts off again when I drive.

Many CIS VW / Audi products run the cooling fan after shutdown. It helped with the CIS hot re-starting issues. They have a temp sensor attached to the valve cover and a simple relay that cuts out after 10 minutes of key off. The fan on my 5000 would run for 5 minutes or so on a warm day when I parked.

-J

I do not think this is a hijack (sorry if it is) but how about hooking up an electric fan to my 190 in place of the water pump driven fan? I live in TX and the summer eat s quite hard. The engine has to heat up to 106 or so before the secondary (fan in front of the radiator) engages. While driving the engine temp is fine but under stop and go or city driving the temp always hovers around the 106 or higher. I'd like to have more air flow when driving slow or stopped. Electric fan will turn faster and move more air than the primary fn will at idle or low engine speed.

Thanks

This was my solution.....;)

radiator - Benzworld.org - Mercedes-Benz Discussion Forum

How did you do it? What brand/model fan did you use?

No electric fan involved, just a new dual lower temp fan switch.
Read the full thread.....

Just finished the thread.

I had heard bad things about Uro parts. Any issues with the thermostat? I may have missed it but where did you get the plug and pig tails?

I heard that too, but you can different brands...even directly from BMW. Cause that's where I got the plug & pig tails from.

I connected my dual lower temp switch in "parallel" to the stock temp switch. So if the lower temp switch fails, I have the stock switch as backup. Kinda like a "raid" setup on a computer.

No issue with thermo (no sure what you are asking), but it's been replaced with a 79c thermo.

I can recall the little Renault's had that facility;the electric fan staying on for about 5 minutes after engine switch -off.
ad

Reread the thread. How do u book them up in parallel? I thought the thermostat.has to be screwed into the coolant thing? Did u make a new hole?

My concern is still the low engine speed issue. An electric fan would pull aura in quicker win the engine is at low speed or idling.

LOL, you really need to spent MORE than 1/2hr reading the thread. All the info you need and questions you are asking are answered in the thread.

I only need to implement "step 1", found out afterwards I don't need to throw "idle" into the mix.

Ok. Will revisit the thread when I get to a real computer. Im in Vegas for SEMA and only have my smart fon.

Now back to the Aux fan. Wiring the main wire at the fuse panel (Circuit #8) to battery does not let the fan run after the key is shut off. This wire must power another system somewhere first (where the temperature is read) and the power to the fan is controlled there. The wiring diagram shows it goes to a temp switch at the AC system by left headlight, but disconnecting that does not shut fan down.

I live in the Palm Springs, CA area where the summers hit 115F every year. My solution to engine heat the last 10 years has been raising the hood after parking in my garage. This has worked out great. Little if any plastic parts degradation. I even had a battery last 2 years beyond its warranty date.
Anziani
'93 300CE 200K
'95 E420 122K

This trick doesn't work on my M104- I ordered a cool harness and it just caused my temp gauge to read wrong and the car hard started from cold.

Once I got to AZ (PHX exactly) it wasn't needed. Car was fine and didn't run any hotter than usual (100C) even idling in traffic at 122 deg- no joke.

Frankly, between this car and my 2002 S10 truck I thought the Benz would have problems with heat- all over the boards everyone complains. My Chevy was the one that had a hard time with this temps....

..........................Then again C36 cooling system is 100% everything works :)

rjp