Fan Not Working

UK forum for general and technical discussion about the Z3 roadster

Moderator: Gazza

Post Reply
drm
Joined: Tue 20 Aug, 2013 13:52
Posts: 60

  Z3 roadster 1.9i

Fan Not Working

Post by drm » Mon 26 Aug, 2013 14:57

I have a 2002 1.9 Right Hand Drive Z3 with no air con

The problem is in stop/start traffic - overheating - the fan isn't coming on.

So I checked the fuses they look fine (16 and 48 no fuse 40 in the car)

Next I have started to look at the fan switch - I am trying to by pass this switch to test it by taking off the connector at the switch.

I have connected the brown wire to the black/green and the fan has come on.

but when i connect the brown wire to the brown/blue no fan.

does this mean the fan is coming on normal or high speed ?

p.s. I have had a look at the relays as well and I have switch the normal speed relay with another one to test it but no difference.

am I testing the fan switch properly (p.s. I have also changed the switch but still no joy).

resunoiz
Joined: Tue 04 Sep, 2012 17:12
Posts: 162

  Z3 roadster 1.9

Re: Fan Not Working

Post by resunoiz » Mon 26 Aug, 2013 16:06

check the hi-speed relay ;) even if looks ok, try to change it ;)
it controls the lo and hi speed too :D

drm
Joined: Tue 20 Aug, 2013 13:52
Posts: 60

  Z3 roadster 1.9i

Re: Fan Not Working

Post by drm » Mon 26 Aug, 2013 17:00

Hi - ok I'll try that - I don't think there is one I can swap with so I'll get a new one - where is the best to get one -does it have to be the dealer ?

resunoiz
Joined: Tue 04 Sep, 2012 17:12
Posts: 162

  Z3 roadster 1.9

Re: Fan Not Working

Post by resunoiz » Mon 26 Aug, 2013 17:06

drm wrote:Hi - ok I'll try that - I don't think there is one I can swap with so I'll get a new one - where is the best to get one -does it have to be the dealer ?
no, not possible swapping with this one. to the dealer, not a big waste of money :wink:

drm
Joined: Tue 20 Aug, 2013 13:52
Posts: 60

  Z3 roadster 1.9i

Re: Fan Not Working

Post by drm » Mon 26 Aug, 2013 20:22

Ok thanks I'll buy one and give it a try

drm
Joined: Tue 20 Aug, 2013 13:52
Posts: 60

  Z3 roadster 1.9i

Re: Fan Not Working

Post by drm » Wed 28 Aug, 2013 14:54

I replaced the high speed relay but still the fan doesn't come on

does anyone know if I am jumping the switch correctly ? do I always take a wire from the brown cable to one of the other ones ?

not sure what else can be wrong ?

at the fan itself there is a connector - does this have a resistor in it ?

User avatar
BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2225

  Z3 roadster 1.9

Re: Fan Not Working

Post by BladeRunner919 » Wed 28 Aug, 2013 15:54

Are we talking about the switch in the side of the radiator? If so, when it gets to it's higher temperature trigger, it actually connects all three pins together. However, I'm not sure that's fundamental to the function of the fan, but rather just how the switch works. I think jumping one or other to earth should have the desired effect, as you have been doing.

drm
Joined: Tue 20 Aug, 2013 13:52
Posts: 60

  Z3 roadster 1.9i

Re: Fan Not Working

Post by drm » Wed 28 Aug, 2013 20:18

Yes this is the switch at the side of the radiator.

Thanks for the info I might try connecting all 3 together

So if I am jumping this correctly and have checked the fuses and relays then I think I will check the connecting onto the fan next.

resunoiz
Joined: Tue 04 Sep, 2012 17:12
Posts: 162

  Z3 roadster 1.9

Re: Fan Not Working

Post by resunoiz » Wed 28 Aug, 2013 21:29

if you connecta all 3 wires, should start the hi-speed speed, but if you point the brown wire with one at a time, you have to hear the 2 speeds too. mayb is a fan problem, or a corrupt wire...the lo-speed relay is ok? the AC one?

connecting the poles under the relays, the fan comes on at the 2 speeds?

drm
Joined: Tue 20 Aug, 2013 13:52
Posts: 60

  Z3 roadster 1.9i

Re: Fan Not Working

Post by drm » Fri 30 Aug, 2013 12:11

Good news and bad news

I found out that when trying to jump the fan switch - when testing the normal speed fan - you actually need to have the engine temperature high - I was testing it cold. So when I tested it with the temp gauge needle just after the 12 o'clock position - the fans comes on.
The reason for this is that there is another temp switch on the engine block that sends the temp to the engine management unit and also the gauge on the instrument cluster.

So good news when jumping the fan switch I can get the fan working on both speeds.

So this would point to the fan switch being faulty - so I replaced it and it still doesn't come on by itself when engine reaches required temp.

So 2 possibilities: -

1. loose connection when connection the fan switch (but seems ok)

2. somehow the fan switch isn't recording the radiator temp at a high enough level.

Now this might be possible because when I changed the switch only a small dribble of coolant come out - I was expecting more ? any ideas ?

Might be a airlock - but I did try bleeding the system

User avatar
BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2225

  Z3 roadster 1.9

Re: Fan Not Working

Post by BladeRunner919 » Fri 30 Aug, 2013 13:22

The fan must operate differently on the M43 to the M44. On the M44 the fan runs with the switch jumped irrespective of engine temp.

Are you sure the engine is actually hot enough to start the fan up? It does need to be pretty warm to kick in - it doesn't run in normal operation. As for an airlock, is the radiator full - just undo the small bleed cap to check (when it's cold, of course).

User avatar
BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2225

  Z3 roadster 1.9

Re: Fan Not Working

Post by BladeRunner919 » Fri 30 Aug, 2013 14:57

I've had a look at the ETM, and there really is nothing to suggest that the fan is in any way influenced by the sensor for the temp gauge on your car - the wiring and function looks the same on all cars in all years as far as that fan goes.

I'm assuming you have no mechanical fan, and that the electric fan is between the radiator and the engine (not in front of the radiator)?

resunoiz
Joined: Tue 04 Sep, 2012 17:12
Posts: 162

  Z3 roadster 1.9

Re: Fan Not Working

Post by resunoiz » Fri 30 Aug, 2013 15:00

BladeRunner919 wrote:The fan must operate differently on the M43 to the M44. On the M44 the fan runs with the switch jumped irrespective of engine temp.

Are you sure the engine is actually hot enough to start the fan up? It does need to be pretty warm to kick in - it doesn't run in normal operation. As for an airlock, is the radiator full - just undo the small bleed cap to check (when it's cold, of course).
I'm with Bkladerunner.

what serial has the termostat you changed?
it' s the first time I hear that with the M43 you have to wait for car heating to have the fan operating...

drm
Joined: Tue 20 Aug, 2013 13:52
Posts: 60

  Z3 roadster 1.9i

Re: Fan Not Working

Post by drm » Fri 30 Aug, 2013 15:30

Hi - I'll double check this but I have tried many times to jump this switch when the car was cold - I'll test that again in case something else happened.

Yes it is an electric fan between the radiator and the engine.

The expansion tank is topped up to the level.
With the engine cold and the car stopped - when I open the bleed screw - should coolant flow out of the bleed screw ?

User avatar
BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2225

  Z3 roadster 1.9

Re: Fan Not Working

Post by BladeRunner919 » Fri 30 Aug, 2013 16:08

drm wrote: With the engine cold and the car stopped - when I open the bleed screw - should coolant flow out of the bleed screw ?
Not if it's fully cold.

User avatar
Brian H
Joined: Tue 16 Dec, 2008 19:55
Posts: 2504

  Z3 roadster 3.0i

Re: Fan Not Working

Post by Brian H » Fri 30 Aug, 2013 17:37

Open the bleed screw and run the car up to temp, keep adding coolant until it just flows out of the bleed screw. Make sure you have the heater switched all the way to hot in the car.

For reference the circuit diagram below is for the auxiliary fan circuit.

Image

kkkrisss
Joined: Thu 13 Jan, 2011 09:15
Posts: 189

  Z3 roadster 1.8
Location: Munich
Contact:

Re: Fan Not Working

Post by kkkrisss » Fri 30 Aug, 2013 18:55

Is this the wiring diagram for M43 specifically? Coz I do not see the ECU and I am pretty sure it is involved in the operation of the aux fan..

User avatar
Brian H
Joined: Tue 16 Dec, 2008 19:55
Posts: 2504

  Z3 roadster 3.0i

Re: Fan Not Working

Post by Brian H » Fri 30 Aug, 2013 19:29

kkkrisss wrote:Is this the wiring diagram for M43 specifically? Coz I do not see the ECU and I am pretty sure it is involved in the operation of the aux fan..
Hi kkkrisss,

The diagram was pulled from the 2001 ETM which covers all models, no specific reference to M43. I do not see a reason to go through the ECU for the auxiliary fan, just quite a simple circuit that is controlled by either a pressure switch which uses the high speed relay or a temp switch which uses either the normal speed rear or high speed relay depending upon water temp.

Brian

kkkrisss
Joined: Thu 13 Jan, 2011 09:15
Posts: 189

  Z3 roadster 1.8
Location: Munich
Contact:

Re: Fan Not Working

Post by kkkrisss » Fri 30 Aug, 2013 19:43

As far as I remember the ECU energizes the low speed relay...
I could be wrong of course.

User avatar
Southernboy
Joined: Thu 07 Oct, 2010 13:39
Posts: 6423

  Z3 roadster 3.0i
Location: Johannesburg

Re: Fan Not Working

Post by Southernboy » Fri 30 Aug, 2013 20:42

The ECU doesn't have control of the fan...I have replaced my radiator thermo-switch from the OEM 98 Degree switch with the e30 88 Degree switch...and when that baby hits 88'ish...the fan does it's cooling...I've tossed the Viscous fan...that's why I changed the thermo switch.. just so it will turn the fan on at a lower temp than OEM will do.
From that you will deduce the fault described above is a relay or a thermo-switch...and as I understand the BMW set-up..there are 2 circuits..one is via the aircon switch on the centerconsole and the other as I described above. The fan itself in this model, may have a further innovation which is a CU built into the fan center hub alongside the motor. In some cars (Merc) I have seen that this system allows a variable speed control which is activated by the CU responding to engine coolant temp...which is essentially the same temp sender / switch unit as I described above as a thermo-switch fitted into the side of the Radiator. If your car has such an innovation you would need to examine the correct functioning of that part to determine the origins of your problem. Unortunately, my model doesn't have such a system..but I have been referred to a company here that fits such systems and it truly replaces the loss of the mechanical viscous fan, and plan to have my car modified to safely lose the mechanical fan and free up some engine power.
"Normal is overrated"
Image

Z3 Upgrades and Additions

kkkrisss
Joined: Thu 13 Jan, 2011 09:15
Posts: 189

  Z3 roadster 1.8
Location: Munich
Contact:

Re: Fan Not Working

Post by kkkrisss » Sat 31 Aug, 2013 07:23

Managed to find the engine cooling wiring diagram for the 4 cyl engines...but i cannot upload it..
According to the Bentley manual there is ECU involvement... Also there is a resistor in the fan that is related to the low speed. I guess if the resistor is blown the fan will not operate...

User avatar
Brian H
Joined: Tue 16 Dec, 2008 19:55
Posts: 2504

  Z3 roadster 3.0i

Re: Fan Not Working

Post by Brian H » Sat 31 Aug, 2013 08:04

kkkrisss wrote:Managed to find the engine cooling wiring diagram for the 4 cyl engines...but i cannot upload it..
According to the Bentley manual there is ECU involvement... Also there is a resistor in the fan that is related to the low speed. I guess if the resistor is blown the fan will not operate...
I can see a resistor in the fan motor in the ///M vehicles, I can also see the pressure switch is connected to the evaporator controller for those car with AC, but cannot see any connection to the ACU, I will see if I can dig around and find a bentley diagram out of curiosity.

User avatar
Southernboy
Joined: Thu 07 Oct, 2010 13:39
Posts: 6423

  Z3 roadster 3.0i
Location: Johannesburg

Re: Fan Not Working

Post by Southernboy » Sat 31 Aug, 2013 10:54

I've just been at my BMW mechanic and briefly discussed the fan issue...All Z3's were fitted with a dual switch fitted into the side of the radiator...some of the last e36's had electric fans vs Viscous fans...these have a resistor fitted to the fan in the center...looks like a copper coloured tube aprox 100mm long...this resistor actuates the 1st / 2nd speed but in all instances the dual thermo switch fitted to the radiator is the activator which opens / closes the electrical circuit to the fan..with the exception of the AC switch on the console.
It also seems that the last e36 models were fitted with electric fans which operated as the primary cooling fan in place of the viscous clutch fans...these are a simple and direct replacement for a mechanical fan and require minimal rewiring from the OEM circuitry...
So...anyone who is driving a 6 cylinder BMW e36 with an electric fan, please contribute with the relative part number for this fan...I need to source one too....
"Normal is overrated"
Image

Z3 Upgrades and Additions

drm
Joined: Tue 20 Aug, 2013 13:52
Posts: 60

  Z3 roadster 1.9i

Re: Fan Not Working

Post by drm » Sun 08 Sep, 2013 20:05

I have checked this and it is correct to say that you can jump the fan switch connector when the car is cold.

I have since managed to jump this switch and I can now see the fan coming on in normal and high speed - so that is good and narrows the problem down a bit.

Having replaced the fan switch and made sure the radiator is filled I think I might have a loose connection on the connector that goes onto the fan switch.

I was thinking of trying to test this by removing the switch from the radiator and trying to heat this switch.

I would be doing this with it connect up - what is the best way to heat this switch ?

Blow torch on the end of the switch ? Or boiling water in a container and dip the switch into it ?

Any ideas what is best

User avatar
Southernboy
Joined: Thu 07 Oct, 2010 13:39
Posts: 6423

  Z3 roadster 3.0i
Location: Johannesburg

Re: Fan Not Working

Post by Southernboy » Sun 08 Sep, 2013 20:10

....def not a blow torch!!!!!! a gas lighter will work perfectly... :wink:
"Normal is overrated"
Image

Z3 Upgrades and Additions

drm
Joined: Tue 20 Aug, 2013 13:52
Posts: 60

  Z3 roadster 1.9i

Re: Fan Not Working

Post by drm » Sun 08 Sep, 2013 20:52

Ok I will try a gas lighter

User avatar
Brian H
Joined: Tue 16 Dec, 2008 19:55
Posts: 2504

  Z3 roadster 3.0i

Re: Fan Not Working

Post by Brian H » Sun 08 Sep, 2013 21:08

A cup of boiling water? Dip in the part that is usually in the radiator then test.

User avatar
Southernboy
Joined: Thu 07 Oct, 2010 13:39
Posts: 6423

  Z3 roadster 3.0i
Location: Johannesburg

Re: Fan Not Working

Post by Southernboy » Mon 09 Sep, 2013 05:16

...a cup of boiling water will work, if you can keep the water hot enough.
"Normal is overrated"
Image

Z3 Upgrades and Additions

drm
Joined: Tue 20 Aug, 2013 13:52
Posts: 60

  Z3 roadster 1.9i

Re: Fan Not Working

Post by drm » Mon 09 Sep, 2013 16:21

Good news I was able to test this using a cup of boiling water and what I found is that the old switch was indeed not working and the new switch works perfectly (no problem with connections).

So from this it must mean that there is no hot water getting to the switch when it is in the radiator.

So I guess it is the filling/bleeding that something is not right ?

When the car is cold the expansion tank is filled up to where it should be

From here what is the best way to bleed/top up if necessary ?

1. Start the car and get it to a temp where the needle is half way (thermostat will be open) and also set the heater to the full heat position.

From here what is best to do ?

question are :-

should the engine be running or not

should the bleed screw (on top of expansion tank) be opened slightly or removed

should the expansion tank lid be removed

User avatar
Brian H
Joined: Tue 16 Dec, 2008 19:55
Posts: 2504

  Z3 roadster 3.0i

Re: Fan Not Working

Post by Brian H » Mon 09 Sep, 2013 18:07

Hi drm,

Below is the procedure from the BMW TIS manual.
extact from BMW TIS wrote:
Note: Before filling, switch on ignition, set heater control to maximum temparature and set fan speed to slow. This opens heating valves and installed auxiliary water pump runs if necessary.

Perform Filling Operation Slowly

Fill expansion tank completely and wait until coolant emerges at vent point/s without bubbles. Close bleed screw(s)
I think the important bit is to get all the air out of the system at the bleed screw on the expansion tank.

HTH

drm
Joined: Tue 20 Aug, 2013 13:52
Posts: 60

  Z3 roadster 1.9i

Re: Fan Not Working

Post by drm » Mon 09 Sep, 2013 21:19

Ok so switch on ignition - so engine is not running

Temperature control to maximum and blower fan speed to slow - position 0 or 1 I guess will do

Fill expansion tank completely - so I take it you leave the cap off the expansion tank will you do the whole process.

Thinking about this steps what happens if you complete the whole process and you expansion tank has been filled up too much - bit of a pain to remove it

Wait until coolant emerges at vent point - so still not sure if bleed screw should be open a bit or totally removed

But I will give it a try and see

drm
Joined: Tue 20 Aug, 2013 13:52
Posts: 60

  Z3 roadster 1.9i

Re: Fan Not Working

Post by drm » Sat 14 Sep, 2013 16:01

Fan now working - success

Thanks to everyone that replied

It was the fan switch in the end and also proper filling/bleeding of the system.

An interesting part of the filling bleeding was when the coolant was too full as I mentioned in a previous post.

The steps I did we're (these were the steps from the Bentley manual)

With ignition on and heater set to warm temp and bleed screw open (not removed) keep filling with coolant until coolant comes out of the bleed screw.
This only happens when you have totally filled the expansion tank.
When coolant comes out of the bleed screw (no air bubbles in it) - close the bleed screw.

Then open bleed screw and start the engine again once coolant with no air bubbles comes out of the bleed screw - close the bleed screw.
Then is says stop the engine and let the engine cool down.
Once it has cool check the coolant level
The problem I found was the coolant level was still at the top of the expansion tank so I had to take some out - not sure if this is normal or not

But main thing is I put it to the correct level and then ,got it to a hot temp and could feel the fan switch getting hot and then the fan came on.

User avatar
Brian H
Joined: Tue 16 Dec, 2008 19:55
Posts: 2504

  Z3 roadster 3.0i

Re: Fan Not Working

Post by Brian H » Sun 15 Sep, 2013 09:27

drm wrote:Fan now working - success

Thanks to everyone that replied

It was the fan switch in the end and also proper filling/bleeding of the system.

An interesting part of the filling bleeding was when the coolant was too full as I mentioned in a previous post.

The steps I did we're (these were the steps from the Bentley manual)

With ignition on and heater set to warm temp and bleed screw open (not removed) keep filling with coolant until coolant comes out of the bleed screw.
This only happens when you have totally filled the expansion tank.
When coolant comes out of the bleed screw (no air bubbles in it) - close the bleed screw.

Then open bleed screw and start the engine again once coolant with no air bubbles comes out of the bleed screw - close the bleed screw.
Then is says stop the engine and let the engine cool down.
Once it has cool check the coolant level
The problem I found was the coolant level was still at the top of the expansion tank so I had to take some out - not sure if this is normal or not

But main thing is I put it to the correct level and then ,got it to a hot temp and could feel the fan switch getting hot and then the fan came on.
Glad you got it sorted.

Ricky G
Joined: Fri 08 Mar, 2019 15:23
Posts: 1

  Z3 roadster 2.8

Re: Fan Not Working

Post by Ricky G » Fri 18 Oct, 2019 15:15

On my 98 Z3 2.8 I had to flush the radiator before the temp switch would get hot enough to work. I replaced temp switch ,relays and thermostat none of which fixed the problem. I could have saved time and money if I had flushed first but I miss diagnosed as a electrical problem. Hope this helps someone.

Post Reply

Who is online

Users browsing this forum: No registered users and 2 guests