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Discussion Starter · #1 ·
the aux fan doesn´t works i tested wires and fuses are good and fan are good i think is something with a sensor or somenthing like that, the fans and the fuses and wires are good i tested all that, what can it be thanks.

other problem in my truck is the suspension is noising i check ans it good too but it sound like a old car what do you think somebody toldme that this model of year is like this
 

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'07 C280 4matic, '06 530i, '98 ML320
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Is the AC working fine and the aux fan not running?

Several things can cause the aux fans not to come on - low refrigerant is one of them. Check the refrigerant pressure using a gauge. When you switch on the AC, does the compressor engage? the clutch should engage when AC is switched on.


About the suspension squeaks - where exactly is the noise coming from? front? rear? The rear springs are known to make noises as they age. Torsion bars also make noises. If the bushings are worn, anti-sway bars also make noises.
 

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Discussion Starter · #3 ·
ok thank look the a/c works great th eproblem is that the aux fan doesn´t start automatic a it have to do on and off automatic, i have to bypass with wire from a fuse that have 12V when you pass key on to the relay of aux fan but they are on all time even the a/c be turn off of course when i take te key out they turn off, so there yo see that they works but no in the correct way
 

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Update your profile with model and production date.

Fan is turned on based on pressure sensor located in hose just before condenser inlet or engine temperature. Fan relay is triggered by AAM All Activity Module.

Try replacing relay first. Do you have volt meter or test light?
 

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Discussion Starter · #5 ·
ok i think that is yhe causes i testes the relay changing with other from the same truck and is ok i think can be like the computer or that sensor that you say it´s ml320 98, i need more information about that sensor can you send photos or something like that
 

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What is high side refrigerant pressure? What is outside temperature?

Pressure sensor is located in high pressure hose leading from compressor to condenser just to the right of left headlight.

Is there power at pin 3 of k26 relay? Is there power at pin 2?
 

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ML320 (1999), A160 Elegance (2004), C200 (2012)
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What is high side refrigerant pressure? What is outside temperature?

Pressure sensor is located in high pressure hose leading from compressor to condenser just to the right of left headlight.

Is there power at pin 3 of k26 relay? Is there power at pin 2?
Hi I have the same issues. A/C works fine. Auxillary fans do not switch on and are receiving no voltage. The fuse was blown and I replaced it with no change to the auxillary fan (still not switching on).

At k26 I get full power (14V) at pin 3 but only 0.5V at pin 2. What does this indicate?

I appreciate any help that you can give.:confused:
 

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Hi I have the same issues. A/C works fine. Auxillary fans do not switch on and are receiving no voltage. The fuse was blown and I replaced it with no change to the auxillary fan (still not switching on).

At k26 I get full power (14V) at pin 3 but only 0.5V at pin 2. What does this indicate?

I appreciate any help that you can give.:confused:
And what do you get at pin 1? It should also be B+. If there is B+ at pins 1 & 3 then swap K26 with a similar relay.
 

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And what do you get at pin 1? It should also be B+. If there is B+ at pins 1 & 3 then swap K26 with a similar relay.
Hi There.

I get no voltage at pin 1. I have swopped the relay with another similar relay and still get no auxillary fans turning on. I am assuming that the fans turn on as soon as the A/C is on and set to lowest temp. I have let the car run for 10min or so.:confused:
 

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Just a clarification. Terminals in fuse box are numbered according to DIN 72552.
30 battery
87 output of the relay to component
86 relay coil + (battery)
85 relay coil - ground from controller or switch

.
 

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Just a clarification. Terminals in fuse box are numbered according to DIN 72552.
30 battery
87 output of the relay to component
86 relay coil + (battery)
85 relay coil - ground from controller or switch

.
Does that mean if you short out 30 and 87 it will make the auxillary fans switch on?
 

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Yes, it will.
I shorted out and the auxillary fans run fine. So at least i know they work. I unplugged the refrigerant sensor behind the left headlight and that results in no cool air. Once plugged in it cools again. What else could be the issue as to why the auxillary motors do not switch on?
 

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I shorted out and the auxillary fans run fine. So at least i know they work. I unplugged the refrigerant sensor behind the left headlight and that results in no cool air. Once plugged in it cools again. What else could be the issue as to why the auxillary motors do not switch on?
If fan clutch is good, outside temperature is moderate or refrigerant is low fans will not come on. There is no need. You would need SDS to log into AAM and look at actual values for refrigerant pressure. In other thread Jim posted criteria for fan operation.
http://www.benzworld.org/forums/w163-m-class/1573697-1999-ml430-electric-fans-2.html#post5022743
 

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If fan clutch is good, outside temperature is moderate or refrigerant is low fans will not come on. There is no need. You would need SDS to log into AAM and look at actual values for refrigerant pressure. In other thread Jim posted criteria for fan operation.
http://www.benzworld.org/forums/w163-m-class/1573697-1999-ml430-electric-fans-2.html#post5022743
Hi. Thanks for the great info so far.
When you say fan clutch, are you refering to the main engine cooloing fan. If so then yes this one works fine as it was only replaced a few months ago and always starts up when starting the car. Where is the temperature sensor for the A/C?
 

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Hi. Thanks for the great info so far.
When you say fan clutch, are you refering to the main engine cooloing fan. If so then yes this one works fine as it was only replaced a few months ago and always starts up when starting the car. Where is the temperature sensor for the A/C?
I am referring to belt driven fan. There is no refrigerant temp. sensor. Engine temp. arrives at AAM as CAN data.
 

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It is apparent that the diagrams that myself and Witek posted are in conflict (relative to pin #'s) but regardless of which diagram you use, it requires two B+ circuits for the relay to activate.

One at pin 30 (which you have) and another at either pin 85 or 86, which I don't think you have. Please recheck for B+ at both pins.
 

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I am assuming that the fans turn on as soon as the A/C is on and set to lowest temp. I have let the car run for 10min or so.:confused:
Your assumption is not correct. Primary cooling is by the belt fan. Axillary fans turn on only if the belt fan is not sufficient.

When you say fan clutch, are you refering to the main engine cooloing fan. If so then yes this one works fine as it was only replaced a few months ago and always starts up when starting the car.
I bet you are used to hear the noisy axillary fans. But you installed a brand new fan clutch and wonder why the auxiliary fans are off. Because the the belt fan is cooling the refrigerant much more efficiently after fitted with a new clutch.
 

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Aux fans not working

I found after vac and charge ac aux fans still dont come on. I found the fuse was blown. Now much colder ac and aux fans run whenever ac compressor runs. Id like to find info on the 40amp fuse/ wiring upgrade. Any ideas?
 

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I found after vac and charge ac aux fans still dont come on. I found the fuse was blown. Now much colder ac and aux fans run whenever ac compressor runs. Id like to find info on the 40amp fuse/ wiring upgrade. Any ideas?
Please UPDATE YOUR PROFILE in USER CP.
 

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