XSeries-forum

I take it, that the fan controller is the module that is part of the switch block
that has the 4x4 switch & seat heating switches etc

I have a multi tester that has an oscilloscope function, so will test that too....

Question...
When the AC is switched on at the snow-flake button.... is the AC fan supposed to switch on and stay on,
or
can the module adjust the fan speed and operate the fan on/off when it decides to ?

2nd question...

Does the interior fan need to be at maximum speed to make the front pusher AC fan work.???

Q1:  I get the impression that it does but at low speed.  As everything warms up so the fan turns faster.  I have not been able to find anything on exactly how the system works or what each component does.

Q2:  Pass, got to be worth a try though.

Is the fan controlled by a pressure switch as Temp/Pressure rises in the system the fan adds cooling at the condenser radiator? Just a thought

There is a pressure switch on the system.  Not sure where it is hidden though.  It runs on the 'high side' of the system and stops the compressor if there isn't enough pressure (usually low gas) in the system.  As your compressor clutch seems to work it sounds like the pressure is OK.

A quick check on the low side port with the tool from Halfrauds will confirm.

You may remember I bought a top up gas & gauge thingy from Halfords last year... the pressure was OK, but topped it up to the max level.

The AC can freeze the balls off a Brass Monkey, but only when rolling - no damned fan.

I don't want a repeat of the traffic jam roastings of last year - want the AC to work when stationary...lol

I thought you had, but was just checking.....

So it's got to be the wiring or pulse train or controller.  I think the speed controller on the fan will probably use PWM but finding hard data on the system is proving fruitless.

You almost need another X to borrow bits off and see what fixes it.  Not ideal.

Maybe get another dash/control panel switch block, and see if that does anything ?

Hi not sure if you are still seeking out a solution to this problem? I had the same problem with my air-con on my 2003 3.0i X5 Sport just after acquiring it a couple of years ago.
I took out the front pusher fan which was not working and could see that in the center of the fan the motor was exposed to the elements and was packed with capacitors encased in resin. It was immediately obvious that the capacitors had bulged with age and were no longer serviceable rendering the motor useless. I looked at dismantling the fan to change the capacitors but it quickly became obvious that it would be a destructive exercise. Baulking at the cost of a dealer replacement I purchased a new replacement from eBay in the USA and paid the shipping which was all together substantially cheaper. The new fan worked instantly bringing the air con back to full functionality. Personally I would not recommend a second hand fan as they will all be suffering to a greater or lesser extent from the same problem. I hope this info assists.

Hi Squealy,

Good info... but tried this one already... and concluded it is a signal error...
But gotta work out where the signal comes from in the 1st place.

Finding the source of the fan trigger signal is the next hunt... if you got any information ??

Question  any one....

The signal wire to trigger the AC fan on the front of the vehicle...
Is the signal a voltage or a pulsed PWM signal...
Im wondering if it is simply a varied voltage because the guts of the fan are unlikely to have decoding electronics to decode a signal to set the rotation speed of the fan motor...

Looking into the motor guts, it is not sealed or protected... so im guessing the signal or whatever is simoly ON or OFF....

Any suggestions before I fry a fan motor ??