Sword Failure Question

[John B.]

All speeds on the heater blower in our 1990 535i are out. Blower works with outside power/ground & fuses/blower relay are good. From what I've read the typical failure mode for the sword in my 12/89 car is 1/2/3 out but full power still functioning. Can it fail & take out all functions or would it have to be the dash switch assy.? Or??

[Bill R.]

Hi John, I don't know if you got my mail or not but here is a picture of the relay inside the sword handle that controls the high speed. If the solder joints are cracked in the sword where that relay is mounted you won't have high speed

[shogun]

http://www.bimmernut.com/forum/7-ser...centrated.html

[John B.]

Thanks Bill & Shogun. I opened up the sword handle & looked at the solder joints with a magnifying glass and all looked good. Nevertheless I resolded all the relay & plug connector joints but it didn't make any difference. If I close the relay manually the blower does run at full speed but I noticed that the fan switch has no control at this point as the blower will run with the switched turned completely off. Normal? Does this eliminate the sword as the cause of the problem or just mean that the problem is elsewhere on the board?

[shogun]

here is a wiring diagram of the sword Heizschwert

If I close the relay manually the blower does run at full speed but I noticed that the fan switch has no control at this point as the blower will run with the switched turned completely off. Normal? Does this eliminate the sword as the cause of the problem or just mean that the problem is elsewhere on the board?

I assume the problem is somewhere else on the sword. I would change the usul parts.

In the "MAX" position, the blower runs slightly faster than in the controlled range. This is due to the relay, which bridges the FETs at "MAX". To find the defective FET, all FETs must be unsoldered and tested or replaced. With two fingers alternately touch 1 and 2 (AN) and 1 and 3 are (AUS). They are BUZ71, BUZ11 can also be used.

[John B.]

What I forgot to mention in my last post is that I had to feed 12v to the board's blue/black wire contact point in order for the relay to run the blower when I closed it manually. The ignition switch sends 12v to the dash heat/fan switch assy & from there it should be sent to the sword through the blue/black wire when the fan switch is turned on. Without this the relay isn't activated so I'm going to figure out why I don't have the 12v feed at the sword & correct that issue before I worry about possible issues in the sword. Thanks for the link to the diagrams.

[John B.]

The cause of the no high speed fan function was obvious once I opened up the dash control module. On the early E34s like mine all 3 functions (fan, driver heat, pass. heat) are in one unit, no separate fan switch assy. The drivers heat & fan switch both have a white plastic actuator on the shaft that trips a switch at the full on setting. The actuator on my fan switch had broken & was laying loose inside. I moved the factory actuator from the heat shaft to the fan shaft & then made an actuator for the heat shaft as the full on position is seldom used so it should hold up for a few years.

Here's a couple photos of the inside after moving the stock actuator.

[shogun]

Never disassembled that version of control module, searched a bit and found more pics here
Replacing the E34 blower fan and temperature light bulb

[John B.]

Yup, that's it. Installed a ProgRama reman. sword & new blower fan. All is well & the E34 & wife are warm again.