Mercedes-Benz Forum banner

1 - 18 of 18 Posts

·
Registered
Maserati Quattroporte, CL600, S500, BMW 330cic, E65 BMW 750LI. Dodge Ram
Joined
·
883 Posts
Discussion Starter #1 (Edited)
^^^SOLVED^^^^ Hello fellow members,

I replaced my radiator on monday. On wednesday when the outside temps rose above 85 I believe I cracked my replacement radiator.

Can someone explain to me how these two fans work? I have a crack on the driverside of the radiator and I believe it is because the driverside fan is not functioning properly.

What triggers these two E-fans? How do they work? I noticed the passenger side E-fan shuts off when my engine is at high rpms and restarts when it is in Idle. Thankyou for your help on this issue.


 

·
Premium Member
2004 CLK 240 Coupe
Joined
·
11,377 Posts
The dual fans (M4/m1 & M4/m2) you show are termed the 'auxiliary fans'. The single fan (M4/3) on other W208 models is termed the 'engine/climate control electric cooling fan'

From studying my WIS for your model, it seems that the auxiliary fans have two purposes - incremential cooling of the engine coolant, and also the a/c refrigerant.

To achieve this, 2 inputs are required to either the Engine/Climate control electric cooling fan control module (N65/1), or the Air control module (N76) which directly controls the fans. These are:

a) B12 refrigerant pressure sensor
b) B11/4 coolant temperature sensor

I think that the l/h fan (in your image) is for the a/c, and the r/h is for the engine coolant. You should see an effect if you change the temperature settings on the a/c front panel. If no change there, you could have sensor problems or a fault on N65/1.
 

Attachments

·
Registered
Maserati Quattroporte, CL600, S500, BMW 330cic, E65 BMW 750LI. Dodge Ram
Joined
·
883 Posts
Discussion Starter #3
thankyou keyhole

The dual fans (M4/m1 & M4/m2) you show are termed the 'auxiliary fans'. The single fan (M4/3) on other W208 models is termed the 'engine/climate control electric cooling fan'

From studying my WIS for your model, it seems that the auxiliary fans have two purposes - incremential cooling of the engine coolant, and also the a/c refrigerant.

To achieve this, 2 inputs are required to either the Engine/Climate control electric cooling fan control module (N65/1), or the Air control module (N76) which directly controls the fans. These are:

a) B12 refrigerant pressure sensor
b) B11/4 coolant temperature sensor

I think that the l/h fan (in your image) is for the a/c, and the r/h is for the engine coolant. You should see an effect if you change the temperature settings on the a/c front panel. If no change there, you could have sensor problems or a fault on N65/1.
the driverside fan is the one not spinning. is that for the A/C? The passenger side fan spins intermitently. When the engine heats up, the fan begins to spin.

If I hooked it up to star diagnostics would star locate these faults?

I just dont want to loose anymore radiators.
 

·
Premium Member
2004 CLK 240 Coupe
Joined
·
11,377 Posts
the driverside fan is the one not spinning. is that for the A/C?
I think that the driver's side (US) is for the coolant temp. (but I could be wrong)

The passenger side fan spins intermitently. When the engine heats up, the fan begins to spin.
If the a/c is turned on, that's probably OK. See the WIS drawing about the refrigerant pressure v fan speed. However, I think there could be an error on the drawing. Surely it should read: Less than 16 bar = low speed. More than 20 bar = high speed?

If I hooked it up to star diagnostics would star locate these faults?
That should find bad sensors- yes.

However, why not first pull off the coolant temp sensor (B11/4) and check the resistance. It should be in accordance with the WIS drawing below. If it is 0 ohms or infinity you have a bad sensor. To make life more complicated, there are different W208 a/c systems, but I think that the operation is basically the same.
 

Attachments

·
Registered
Maserati Quattroporte, CL600, S500, BMW 330cic, E65 BMW 750LI. Dodge Ram
Joined
·
883 Posts
Discussion Starter #5
thanks alot keyhole

I think that the driver's side (US) is for the coolant temp. (but I could be wrong)



If the a/c is turned on, that's probably OK. See the WIS drawing about the refrigerant pressure v fan speed. However, I think there could be an error on the drawing. Surely it should read: Less than 16 bar = low speed. More than 20 bar = high speed?



That should find bad sensors- yes.

However, why not first pull off the coolant temp sensor (B11/4) and check the resistance. It should be in accordance with the WIS drawing below. If it is 0 ohms or infinity you have a bad sensor. To make life more complicated, there are different W208 a/c systems, but I think that the operation is basically the same.
The reason I ask about the star-diagnostics checkup is because I am in need of the checkup anyway. I was going to have it hooked up soon, and if this can be diagnosed then it saves time on this and I can work on something else.
 

·
Registered
Maserati Quattroporte, CL600, S500, BMW 330cic, E65 BMW 750LI. Dodge Ram
Joined
·
883 Posts
Discussion Starter #6
I will test the E-fan first

I will test the efans first by swapping them and making sure they arent bad as well.
 

·
Registered
Maserati Quattroporte, CL600, S500, BMW 330cic, E65 BMW 750LI. Dodge Ram
Joined
·
883 Posts
Discussion Starter #8
Thankyou MarcusF

1 - With the car off, insert the key and turn ignition to the second position where the dash lights are illuminated.

2 - Press and hold both "Auto" buttons on the Climate Control unit for approximately 15 seconds.

At this point, both auxiliary fans should be on.
Only one was running. Either I have a bad driverside fan or a bad sensor.
 

·
Premium Member
2004 CLK 240 Coupe
Joined
·
11,377 Posts
do you think that would cause the "ONLY" the second fan not to work properly?
It's possible. They are driven independently from the module.

Make up a short test cable so that the input to fan 1 goes to fan 2, and see what happens. Then try the other way. That should eliminate a bad fan.
 

·
Registered
Maserati Quattroporte, CL600, S500, BMW 330cic, E65 BMW 750LI. Dodge Ram
Joined
·
883 Posts
Discussion Starter #12
I reversed the fans and still the lefty worked

It's possible. They are driven independently from the module.

Make up a short test cable so that the input to fan 1 goes to fan 2, and see what happens. Then try the other way. That should eliminate a bad fan.
When I reversed the cables keyhole still only the left one worked. I did notice corrosion on my driverside fans output connection. it was alot also. the thing was green.

Could this have shorted out my fan? the connector clearly works if it is powering the passenger side fan when switched around.
 

·
Premium Member
2004 CLK 240 Coupe
Joined
·
11,377 Posts
I did notice corrosion on my driverside fans output connection. it was alot also. the thing was green.
Green is probably Verdigris on the copper of the connector, and is sure to make a bad contact. It seems from your experiment that both fans are good, but you have a bad connection to one of them.

You can neutralize Verdigris with a solution of baking soda, and it should return to the copper color and be OK - if it has not corroded the contacts too severely.
 

·
Registered
Maserati Quattroporte, CL600, S500, BMW 330cic, E65 BMW 750LI. Dodge Ram
Joined
·
883 Posts
Discussion Starter #14
I apologize I meant the passenger side (US).

Green is probably Verdigris on the copper of the connector, and is sure to make a bad contact. It seems from your experiment that both fans are good, but you have a bad connection to one of them.

You can neutralize Verdigris with a solution of baking soda, and it should return to the copper color and be OK - if it has not corroded the contacts too severely.
I reveresed the wires not the fans. The RH/passenger (US) fan was still spinning at full speed. The LH/Driverside fan was not turning at all. This has to signal a bad fan. or fan connection.

Even with the corrosion on the Driver side connector it still powered my passenger side fan.
 

·
Premium Member
2004 CLK 240 Coupe
Joined
·
11,377 Posts
Can you disconnect the fan connectors, and use a testmeter to compare the resistance of both fans? If open-circuit, it still could be a break in the fan to connector wiring, of course. :)
 

·
Registered
Maserati Quattroporte, CL600, S500, BMW 330cic, E65 BMW 750LI. Dodge Ram
Joined
·
883 Posts
Discussion Starter #16
ok I will do that

Can you disconnect the fan connectors, and use a testmeter to compare the resistance of both fans? If open-circuit, it still could be a break in the fan to connector wiring, of course. :)
I oreder another fan yesterday so Iwill test all 3 and see what they read.
 

·
Registered
Maserati Quattroporte, CL600, S500, BMW 330cic, E65 BMW 750LI. Dodge Ram
Joined
·
883 Posts
Discussion Starter #17
Thankyou Guys for your help (SOLVED)

My fan was faulty. All I did was reverse the fans once I took them off and only one worked. My other fan must have shorted.

P.S. that fan test trick saved the day.... Sure enough once tested, only one was spinning...
 

·
Registered
2000 CLK430
Joined
·
8 Posts
1 - With the car off, insert the key and turn ignition to the second position where the dash lights are illuminated.

2 - Press and hold both "Auto" buttons on the Climate Control unit for approximately 15 seconds.

At this point, both auxiliary fans should be on.
I just tried this with my car, neither fan turns on. My radiator just cracked yesterday while getting a smog check... it's a Behr, which I'm assuming was replaced by whoever fixed the car (was in a front end collision).

So what should I start checking first when I have the radiator out?
 
1 - 18 of 18 Posts
Top