Stop Blowing Me!

[Flamin'Cow]

Dear All,

I have yet 'another' problem with my '89 535i SE. Was raining the other day and my windshield fogged up, so I used the 'de-fog' and the windshield cleared fine. After it had cleared I pressed the switch to turn it off and it did - however, the fan was still running.

Got home, turned the car off, turned the ignition switch to position '2' and straight away the blower fan came on 'all-powerful', slowly it died away as the little flaps inside closed off the vents, but the fan was still on and making an annoying whistling sound as the air was trying to escape.

So, out came the fuse (No.19) tried it again and the fan was off. Put the fuse back in and 'wrrrrmmmm' the blower strated again. Took out the relay - again it stopped and again when I put the relay beck in it started again!

I have tried turning the blower on using the rotary controller, have tried turning the dials for heat/air-con on and off, pressed all the other button on the air-con control panel BUT STILL THE BLOWER FAN IS RUNNING.

ARGHHHHHH! Why did I choose the 5? - I was happy with the E30 - nice and simple, but this!

...No, no... calm down Flamin'Cow, You know why you chose it - 3.5 litres, manual gearbox and an M5 LSD is why you chose it.....

Any ideas anyone?

Kindest regards

Flamin'Cow

[Bill R.]

. If you remove the sword and open up the handle you'll see this relay, look and see if the contacts have welded themselves together.http://www.bimmernut.com/%7Ebillr/images/swordrelay.jpg




Dear All,

I have yet 'another' problem with my '89 535i SE. Was raining the other day and my windshield fogged up, so I used the 'de-fog' and the windshield cleared fine. After it had cleared I pressed the switch to turn it off and it did - however, the fan was still running.

Got home, turned the car off, turned the ignition switch to position '2' and straight away the blower fan came on 'all-powerful', slowly it died away as the little flaps inside closed off the vents, but the fan was still on and making an annoying whistling sound as the air was trying to escape.

So, out came the fuse (No.19) tried it again and the fan was off. Put the fuse back in and 'wrrrrmmmm' the blower strated again. Took out the relay - again it stopped and again when I put the relay beck in it started again!

I have tried turning the blower on using the rotary controller, have tried turning the dials for heat/air-con on and off, pressed all the other button on the air-con control panel BUT STILL THE BLOWER FAN IS RUNNING.

ARGHHHHHH! Why did I choose the 5? - I was happy with the E30 - nice and simple, but this!

...No, no... calm down Flamin'Cow, You know why you chose it - 3.5 litres, manual gearbox and an M5 LSD is why you chose it.....

Any ideas anyone?

Kindest regards

Flamin'Cow

[brosher]

Did you accidentally enable the fan timer on the obc? With the ignition on press the timer button and then the s/r button. If it is set to 'ON' the fan will continue to run after car shuts off.

EDIT: actually i don't think this feature was on the 89's

[Flamin'Cow]

Thankyou - what is the 'Sword' and where is it?

[Flamin'Cow]

Nah - it only does it when the ignition is 'ON'

[Bill R.]

most e34's use. Some use a resistor pack instead, but most early cars like yours use a sword. Check here at Bruno's for more info (http://www.bmwe34.net/E34main/Maintenance/Electrical/Sword.htm)
Where this screwdriver is is where the sword is, the green electrical plug plugs into the sword. On a US model this is on the passenger side under the dash on the side of the tunnel.http://www.bimmernut.com/%7Ebillr/images/sword2.jpg





Thankyou - what is the 'Sword' and where is it?

[Ross]

I think there is also a relay in the underhood box that feeds the power to fuse 19. That one is easy enough to check.

[Flamin'Cow]

Errr, I don't think I have a 'sword'. Is the 'Sword' the controller that slides left/right to control the power of the fan like on the old E30's?

As stated, when I turn the blower 'ON' its turns on. However when I turn it off, it takes AGES for the little flaps in the vents to move and then the Blower stays on anyway! (but not at full-power)

This is what my dash looks like.....which button is buggered?

http://i31.photobucket.com/albums/c392/flamincow/P1010001-1.jpg

[Bill R.]

likely do have a sword, even if it is right hand drive.





Errr, I don't think I have a 'sword'. Is the 'Sword' the controller that slides left/right to control the power of the fan like on the old E30's?

As stated, when I turn the blower 'ON' its turns on. However when I turn it off, it takes AGES for the little flaps in the vents to move and then the Blower stays on anyway! (but not at full-power)

This is what my dash looks like.....which button is buggered?

[Anthony (M5 in Calgary)]

Mosfets in the sword can also fail in a conductive state - this may account for the fact the fan stays running but at reduced speed. If the relay contacts are fused the fan will stay running at full speed.

[Flamin'Cow]

Thanks for your help - I guess I gotta go take my dash apart now :-(

[Bill R.]

closing ,hence the whistling sound he mentions and the reduced air output... its most likely still blowing full speed though. Its easy enough to check the contacts and thats what i've seen most frequently.




Mosfets in the sword can also fail in a conductive state - this may account for the fact the fan stays running but at reduced speed. If the relay contacts are fused the fan will stay running at full speed.

[Anthony (M5 in Calgary)]

closing ,hence the whistling sound he mentions and the reduced air output... its most likely still blowing full speed though. Its easy enough to check the contacts and thats what i've seen most frequently.

You're probably right there, but it's going to have to come out anyway. Have a look here for mosfet testing:

http://www.uoguelph.ca/~antoon/gadgets/mostest.htm

I repaired a sword recently and added a 56V TVS diode (On Semi 1.5KE56A) across the source-gate and replaced the mosfets with up-rated parts: International Rectifier IRF1310N (purchased from Digi Key). The key to the repair was replacing the driver (LM2903N comparator from ST Micro) as well - this is an 8 pin DIP device in the "handle" of the sword.

I have a photo of how the TVS diode should be intstalled if anybody wants it. The TVS prevents voltage spikes from blowing the gate during transients (turn on/crank).

Up-rated mosfet - way better than the OE parts at 100V Vgs and a lower Rds(on):

http://www.irf.com/product-info/datasheets/data/irf1310n.pdf

[Bill R.]

.
You're probably right there, but it's going to have to come out anyway. Have a look here for mosfet testing:

http://www.uoguelph.ca/~antoon/gadgets/mostest.htm (http://www.uoguelph.ca/%7Eantoon/gadgets/mostest.htm)

I repaired a sword recently and added a 56V TVS diode (On Semi 1.5KE56A) across the source-gate and replaced the mosfets with up-rated parts: International Rectifier IRF1310N (purchased from Digi Key). The key to the repair was replacing the driver (LM2903N comparator from ST Micro) as well - this is an 8 pin DIP device in the "handle" of the sword.

I have a photo of how the TVS diode should intstall if anybody wants it.

Up-rated mosfet - way better than the OE parts:

http://www.irf.com/product-info/datasheets/data/irf1310n.pdf

[Anthony (M5 in Calgary)]

.


Will do. It's on my camera but the $*%& driver set is blown on my WIN98SE home PC. I'll have to get the CF card and upload at the office on my card reader. Might be as late as Monday.:(

[Paul in NZ]

if its going full blast its as noisy as *^%

[Flamin'Cow]

Its not going full-blast, but it is damn noisy.....

Just have to turn the stereo up I guess.....

[Airborne001]

Errr, I don't think I have a 'sword'. Is the 'Sword' the controller that slides left/right to control the power of the fan like on the old E30's?

The Sword is what the control panel operates. You are thinking it is an external controler, when what it really is is the module that the climate control button effects.

Take a good look at that pic with the screwdriver, and then say thank you to Bill for posting such an informative pic.

[Anthony (M5 in Calgary)]

TVS diode (On Semi 1.5KE56AG) across source-gate. This limits spikes to ~48V on the mosfet. Use the International Rectifier IRF1310N mosfet to replace the OE parts - it has 100Vgs rating. In case it isn't clear, the stripe on the TVS is on the side nearest.
http://img.photobucket.com/albums/v11/interalian/113-1378_IMG.jpg

Drill through the sword PCB (1/16"dia) and lay the device leads on the plated areas and solder. If there is conformal coating on the PCB, scrape down to the tin/lead plating before soldering.
http://img.photobucket.com/albums/v11/interalian/113-1377_IMG.jpg

PS: you have to mount the TVS on the underside or the sword won't fit.

[Bill R.]

.
TVS diode (On Semi 1.5KE56AG) across source-gate. This limits spikes to ~48V on the mosfet. Use the International Rectifier IRF1310N mosfet to replace the OE parts - it has 100Vgs rating. In case it isn't clear, the stripe on the TVS is on the side nearest.
http://img.photobucket.com/albums/v11/interalian/113-1378_IMG.jpg

Drill through the sword PCB (1/16"dia) and lay the device leads on the plated areas and solder. If there is conformal coating on the PCB, scrape down to the tin/lead plating before soldering.
http://img.photobucket.com/albums/v11/interalian/113-1377_IMG.jpg

PS: you have to mount the TVS on the underside or the sword won't fit.

[Anthony (M5 in Calgary)]

.

I can send the full size shots if they'd be more useful.