Air Con Pusher fan Not Turning

[kanewesley]

The pusher fan, (the one infront of the engine fan) never kicks in when the aircon is selected. It dont spin up as a test when the aircon is switched on and never comes in during the time the aircon is in use.

The aircon is blowing very cold air.

I have to remember to switch the aircon off each time the car stops moving forward so it dont overheat and blow the compressor like it did once before

Otherwise the aircon is working ok.

I thought if this fan didnt spin up as a self test when the aircon is first switched on...it would inhibit the aircon syatem working.

I have INPA but nowhere is there to turn this fan on to prove it works.

I believe it is ramped up by a square wave pulsed signal.

There is 12v at the 2 main terminals at the fan.

I have red somewhere that this fan has two uses...
a) to keep the aircon syaytem cooled
b) to suppliment the other engine belt driven fan in hot weather...ie when in standing traffic on the motorway.

I asked about the fan operation at the garage where the aircon was repaired recently and was told some fans do a self test and some dont ?????
But still....it NEVER starts and turns


Questions then....
Why is the aircon being allowed to run when this fan dont work and dont work on the self test?

There is 12v at the main power leads to the fan so no fuses (50 amp) can be blown.

It must be in the control side of things...ie...the square wave pulse signal for speed control,

Can it be monitored anywhere in INPA? I can't find anywhere to activate this fan.

Like I said earlier, the aircon blows cold but this fan never operates and if I believe it's only the air rushing through it's radiator fins when the car is moving forward that is keeping the system cooled and I have to remember to switch the aircon off when I am in standing traffic for fear of the compressor going Kaput through the system overheating.

The car is a 200d 3.0D sport facelift model E53 M57 engine

[StuBeeDoo]

I would say that if the aircon is working OK, don't stress about it. I've never been aware of the aux. fan running, or not as the case may be, on any of my cars with aircon - and none of them ever had aircon issues.

If you really are that bothered, take the car for a full aircon service and tell them that you are concerned that the fan doesn't seem to run.

[kanewesley]

With all respect......

You say don't stress about it??
You have never seen a pusher fan running?
It's there for a reason !!!



The system was re-gassed during the red hot summer last year.

The guy who re-gassed it said he was concerned because the pusher fan never came in and he would have expected it to start running within a few minutes as the air con pipage started getting hot as the aircon system started doing it's job.

Sure enough, when stuck in traffic, the system became so hot with no pusher fan cooling it that there was a "Bang"...the engine coughed and the aircon packed up.
The system had become so hot and pressurised that it blew the compressor.

The compressor has been changed for a 2nd hand unit.
The pusher fan has been changed for a 2nd hand unit.
Both were assured to be in working order.
A metal pipe running round the engine was changed for a pinhole in it because it was rubbing on the engine block.
The system re gassed and it's as cold as ice.
It's just that this pusher fan NEVER ramps up.
Thats why I am concerned because without the fan last year, the system overheated , over pressurised and blew the compressor.
I had it to 4 different garages before anyone could mend it to blow cold air.
I don't want all that again !!

Whats puzzling is:-

When aircon is called for, the system should check the compressor and pressures of gas or it will not run.
The pusher fan is given a small ramp up signal to prove it's integrity and that it works otherwise it will not let the compressor start for fear of blowing it through overheating.
Its a catch 22 situation.

But the system DOES start WITHOUT the integrity of the pusher fan being proved.....Why ????

My question was what exactly is the criteria for this fan to run? and how can I prove it though INPA or something?

Why does the aircon work without this proof.?

The advice I got from the garage which finally mended my system was " well....some fans do...some fans don't " !!!!

[wpoll]

You can test the aux fan using INPA. It's in the DDE (Engine) module, under the "Activation" menu. It's the first two items, E-Blower On and E-Blower Off.

[kanewesley]

Thanks....I believe I looked there?

But I'll have another look this morning !

[henrym3]

I agree you can activate the fan in INPA as wpoll says. Have you checked that the area between condenser and rad isn’t stuffed with leaves/debris cos as the condenser heat up the engine fan should ramp up to pull more air through, not much but some. Worse case an independent should be able to put an oscilloscope on it to check if/where the problem is

[henrym3]

Just thought, the inde who said some do turn some don’t will certainly have the gear to check if fan runs. If he doesn’t you need to find somewhere else.

[kanewesley]

Not had chance to put INPA on yet to try and turn the pusher fan on

But....If i remember right, the last time I looked, this facility wasn't there. ? ? ?

The only fan INPA related to which could be switched on with E-Blower On E-Blower Off was the actual blower fan inside the car....and NOT the pusher fan !!
Also, cant see leaves and debris being a problem causing the fan to ramp up because the fan don't ramp up at all.

Maybe the oscilloscope idea is one to try.

[wpoll]

E-Blower item in the DDE is the aux fan. The interior blower is not controlled by the DDE (but by the IHKA).

[kanewesley]

Thanks wpoll....I'll have another look !

[henrym3]

I’m not talking about your aux fan, I’m referring to the viscous fan as heat soak from condenser comes through the radiator it would start to engage more. Ie "ramp up"

[wpoll]

I’m not talking about your aux fan, I’m referring to the viscous fan as heat soak from condenser comes through the radiator it would start to engage more. Ie "ramp up"

Those die too, although they usually either seize and run all the time or the bearing get VERY noisy (like mine did recently), then they seize. Occasionally one will fail in a mode where it no longer speeds up when the hub temp rises (the hub of the coupling gets heated by hot air flowing back from the radiator). This can be checked after a drive when engine is at full temp - stop, pop the bonnet and check the fan is spinning quickly. It often won't respond to temp rises when simply idling as there is no air flow to heat up the hub.

[kanewesley]

How many fans are there???????
The auxillary fan IS the viscous fan !

There is the main engine cooling fan ...belt driven,
There is the blower fan inside the car.
And there is the Auxillary fan, call it what you will, in front of the main belt driven fan, which should ramp up and down with this ridiculous square wave signal which can only be monitored with an oscilloscope.....ahhh an osicilloscope....every home should have one !!!!

[kanewesley]

I connected INPA
DRilling down, there is provision to turn some kind of fan on.

F1 E-Blower ON
F2 E-Blower OFF

when I select either....nothing happens...no fan starts...nothing.

No additional window comes up to set the percentage speed of the fan whatever it relates to it's either On or OFF.
Thats why I believe E-Blower is NOT my aircon system cooing fan otherwise I would have provision to ramp it up and down by entering percentages.

And even if it was the correct fan,,,,there is still nowhere in INPA to check on this square wave signal

I'm voting Brexit and hope BMW will stop sending their ultimate driving machine cars over here !

[wpoll]

The viscous coupling and fan is the one attached to the fan belt, behind the radiator. The aux fan is an electric fan in front of the radiator.

In INPA the e-blower on and off are the only diagnostics available. It either runs 100% or it doesn't. If it doesn't it's dead and there should also be a code for a dead aux fan in the DDE error memory.

There is no way to view the aux fan contol PWM signal duty cycle in INPA - but yeah, you could use an oscilloscope. Won't tell you much though....

The blower in the dash is not part of all this - it is part of the IHKA system and not related (other than via data comms from the DDE and IHKA).

It is my understanding that if the aux fan is dead, the A/C will still run but may blow warm when there is little forward movement, i.e. when sitting in traffic etc.