Hey fellas, I noticed that the aux fans will not kick on when a/c is on on and even when temp is above 95deg! I left the car on and unpluged the coolant fan switch, heard the relay click, and I got 12vdc down at the motors. When I plug in a motor, the voltage drops out! I replaced the red fuse marked 'd' for aux cooling fan and it was no help. I even replaced both fan motors! The relay seems fine, I bench tested it, what else could cause the fans not to kick on? Thank you very much in advance! The car is a '93 300te,

---dirtyhands

__________________
------------------------------------------------------------------------------------
1991 Mercedes Benz w201 190e 2.3 5sp.
1993 Mercedes Benz w124 300te 3.2 M104

For Sale:
2000 Mercedes Benz w210 e320 Wagon
$10,500---Sold!

A/c fan has nothing to do with temp.
It is pressure sensed.
Test #1:
Key ON
Jumper the sw at reciever/drier with the 6" pigtail wire [ jumper at pigtail connectors]
Does low fan come ON ?

__________________
A Dalton

Thanks Arthur for the reply! Yeah I tried jumping that pressure switch out as well as disconnecting the temp switch on the t-stat. The weird thing is that I hear the relay kick on and it provides 12vdc to the motor harness, but if I connect a motor, the power drops out! Its really strange, I even swaped the green relay with one on my 190 (same 5 prong relay) still no help! I am totally lost here! Any help would be great!

----dirtyhands

__________________
------------------------------------------------------------------------------------
1991 Mercedes Benz w201 190e 2.3 5sp.
1993 Mercedes Benz w124 300te 3.2 M104

For Sale:
2000 Mercedes Benz w210 e320 Wagon
$10,500---Sold!

OK

The suspect is the connections at the speed dropping Resistor.

Behind the driver headlamp area is a ceramic resistor.

Test #2:
Key OFF
Take a jumper wire and go from the battery Pos terminal over to each side of this Resistor. Should have High Fan on one side and Low fan on the other,
Look at these terminals good , as I suspect a bad connection...which is causing the V drop as soon as load of motors is applied.

http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2FG17RJ3A2G318PZE9&yearid=1993%40%401993&makeid=MB%40%40MB%40%40X&modelid=300%2DTE%2D002%40%40300TE+Wagon&catid=G%40%40Cooling+System&mode=PA&subcatid=G5040@@Aux%2E+Fan+Resistor&source=www.peachparts.com&clientid=catalog.mercedesshop

__________________
A Dalton

Thanks again Arthur, I ran 12vdc to the resistor, I think your right, I am going to take off the driver side headlight and clean those connections, here is a pic, hopefully it will help some other people!

Attached Thumbnails

 

__________________
------------------------------------------------------------------------------------
1991 Mercedes Benz w201 190e 2.3 5sp.
1993 Mercedes Benz w124 300te 3.2 M104

For Sale:
2000 Mercedes Benz w210 e320 Wagon
$10,500---Sold!

...and what were the results of the test ????????????

__________________
A Dalton

One of those two wires on the resistor, likes to melt itself to pieces. The nuts and thread on either end are usually so rusted, that most of the time, you break some of the porcellain.

__________________
It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D

Thanks again Arthur, you were right on the money! I took off the drivers side headlight and found a broken wire off the resistor. I took out the resistor and cleaned both terminals and recrimped the heavy gage wire and remounted everything! The fans work like a charm! Thank you for your help, I owe you a round of beers! ;-)

Dirtyhands

__________________
------------------------------------------------------------------------------------
1991 Mercedes Benz w201 190e 2.3 5sp.
1993 Mercedes Benz w124 300te 3.2 M104

For Sale:
2000 Mercedes Benz w210 e320 Wagon
$10,500---Sold!

Very Good.

Beers for Years ..............

__________________
A Dalton

Yep,,, if Arthur were near by he would never have to buy another beer. His help has been invaluable over the years.

__________________
95 SL500 Smoke Silver, Parchment 64K
07 E350 4matic Station Wagon White 34K
02 E320 4Matic Silver/grey 80K
05 F150 Silver 44K

Where were all you guys when I used to Drink ?????

..

__________________
A Dalton

Keep tabs on it, there is a good chance the wires will melt again. I used to perform this repair annually on my '93 sedan. Eventually I replaced the resistor and have not had any problems since. My guess is the corrosion causes extra resistance, hence extra heat. Enough to cook the wire and eventually cause its failure. Replacing the resistor is no more work than what you've already done.

- JimY

I second Jim's statement. In the nearly 100k miles of ownership, I've replaced the resistor once (it was bad) and repaired the connection 3 times.

__________________
It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D