A/C Low Fan not working - W140 M104 1995 S320 - Page 2 - PeachParts Mercedes-Benz Forum

mbdavid · #16 01-08-2007, 05:51 PM

Quote:

Originally Posted by 95 S320 LWB

MB DOC,

Thanks for the picture - what is the tube? is it a temperature sensor? I am also a bit confused - are you saying I need to cut it open and rewire the insides with the resistors listed on the TSB? I can probably do that, but just checking...
So, to recap - is this a new assembly I have to build or can I modify the tube with the parts listed? (Thanks for your help!)

Hi
I have the same problem but my two wire short-out and i traced to the back of headlight but I do not know where the two wires connect to.
Please if you can help me or you have diagram .emil it
yavarian2003@yahoo.com

jlas · #17 01-02-2009, 03:22 PM

Hello,

I have the same problem in my S350 turbodiesel 1995 OM603.971 engine...

The "tube" resistor acording to the EPC, is replaced with the 0001583745 resistor.... but in the draw posted by MB DOC, the tube resistor must be replaced with two resistors: the 0001583745 and 0001583945.

Is this ok? Or because my car is an diesel version is just enought one of then?.

Thanks.

Ben Taleb · #18 05-31-2018, 12:06 PM

Hello Gents, I am planing to replaced my tube resistor with the ballast one but the second one has more cables than the tube, any advice how to connect them.

JimF · #19 05-31-2018, 03:52 PM

Not sure about your AC Fan system (2 or 3 speeds) but check the picture here:
https://www.k6jrf.com/R15_R151_dwg1.gif

and

read the section here: https://www.k6jrf.com/MB_CTS.html

My 94 S500 is a three-speed system. For two (2) speed I believe the "short" shown in the picture makes it two speed.

vitop · #20 06-03-2018, 10:27 AM

Quote:

Originally Posted by JimF

As MB Doc said, it's a series circuit. To see this 'visually', look at Menu#18 to the sketch just above the "blue" table (Aux Fans Activation).

The first sketch shows a 'three-speed' system; if you look carefully you'll see an 'extra' wire that goes to R15 resistor. There's no "jumper" bar.

The second sketch shows the 'two-speed' system. Note the jumper bar and only two wires. . . a 'series' circuit.

The resistors are switched in (shown in the schematic) with the Aux Fans according to the following;
"no-resistors-in-series" = High speed
"one-resistor-in-series" = Medium speed
"two-resistors-in-series" = Low speed

I have a really basic question.

How do you know if you have a two speed or three speed system?

JimF · #21 06-03-2018, 01:41 PM

"The first sketch shows a 'three-speed' system; if you look carefully you'll see an 'extra' wire that goes to R15 resistor. There's no "jumper" bar."

The key is the "EXTRA" wire that the 2 speed systems don't have. If you look carefully you'll see an 'extra' wire that goes to R15 resistor. There's no "jumper" bar.

Another way: on a HOT day, idle the car with the AC on and hood closed. The engine s/b COLD. After a while you should hear the Aux Fans increase in speed (2nd speed) and then, as the engine temp climbs, the A/F will switch to high speed.

But the easiest way is to look for the wire between R15 and R15/1.

vitop · #22 06-03-2018, 02:05 PM

Quote:

Originally Posted by JimF

"The first sketch shows a 'three-speed' system; if you look carefully you'll see an 'extra' wire that goes to R15 resistor. There's no "jumper" bar."

The key is the "EXTRA" wire that the 2 speed systems don't have. If you look carefully you'll see an 'extra' wire that goes to R15 resistor. There's no "jumper" bar.

Another way: on a HOT day, idle the car with the AC on and hood closed. The engine s/b COLD. After a while you should hear the Aux Fans increase in speed (2nd speed) and then, as the engine temp climbs, the A/F will switch to high speed.

But the easiest way is to look for the wire between R15 and R15/1.

Thanks Jim:

I'll look. For some reason I thought I had that other version of the resistor that is part of the wiring harness. I'll check it out again. Either way, the fans are not coming on and I need to figure out what is going on (or in this case, not going on)

vitop · #23 06-03-2018, 04:04 PM

Jim:
Looks like I was wrong. I have the two speed setup on my car. I now have to try and find out why they don't run. On my W126, I can jumper the pressure switch on my dryer and the fans will turn on. I am assuming the same is true on the W140? Harder to get to though!

vitop · #24 06-14-2018, 10:24 PM

ok. Stupid Question number 2

On my W126, I can short the two wires going to the dryer switch and the fans run.

I removed the connector on the dryer on my W140, and the connector has three wiring connections. Which need to be shorted to test the fans, or can't you do this on the W140?

I also tried to remove the harness from the temp sensor which makes the fans turn onto high speed on my W126. Nothing on the W140. Not sure if something is wrong or you can't test it that way on the W140.

Anyone have any basic testing to check out what is wrong. I know the fans themselves are good because they come on when connected to 12V

JimF · #25 06-15-2018, 01:42 AM

If I remember correctly, the Aux Fans should come on when you short the pins in connector. Just to be clear; remove the connector over the "blue" sensor and use a piece of wire to short between the pins.

Give that a try and lets us know.

vitop · #26 06-15-2018, 06:04 AM

Quote:

Originally Posted by JimF

If I remember correctly, the Aux Fans should come on when you short the pins in connector. Just to be clear; remove the connector over the "blue" sensor and use a piece of wire to short between the pins.

Give that a try and lets us know.

I'll try that. On the W126, you had to short the wires on the dryer switch but simply removing the connector on the blue sensor turned them on. You did not have to short them (which is kind of strange). I will try to short them on the W140 and see if that kicks them off.

The battery looks like it is weak so I need to now also take care of that!

IGG · #27 11-18-2018, 12:00 PM

Good Afternoon
I have w140,s350d,1995
Problem with ac, very strange
I see ac clutch is engaged and working, but no air coming at all inside
Also both fans are off
Anyone can help,please
Thanks very much in advance
Garret

Hatebreed · #28 04-18-2019, 11:36 PM

I have an 1995 S600. I want to remove the black tube resistor and install the two ballast style. The diagram is not clear as to how to wire the 3 speed Fan. It states there is a third world and no jumper? I have looked at the tube resistor and there is 2 wires going to it. Is there any specific way they are installed? Or is this actually a 2 speed fan on the 1995?