Heater fan problems..

[Art Ford]

I have a 1997 BMW 840ci and I'm unable to adjust the heater/air conditioning fan speed. The fan will only work at full speed. The air blows cold when I've got the air conditioning on and hot when the heaters on, but the fan will only blow at full speed. Any ideas what this could be? Relay? Computer module?

[Timm]

That will be the famous Final-Stage Unit, better known as The Sword because it looks, well, more like a tenon saw really. Being LHD yours is easy to get out (relatively). They are available on Ebay or can be repaired - oodles of information here:

https://www.google.com/search?q=swor...hrome&ie=UTF-8

[TedBobo]

Art, check with Fern, Gary or Taylor. Pretty sure one of them has done this.

[Art Ford]

thank you so much..art

[mr1173]

The fan will only work at full speed.

Seems like a SWORD issue. Easy to fix:
http://www.bimmerboard.com/forums/posts/136145/
http://www.bmwe34.net/E34main/Mainte...ical/Sword.htm

[vet73]

Easy to fix is a relative and very subjective term. This is a doable home job but it is not easy unless you are a contortionist and about 4.5 feet tall. The replace of the sword Is easy, just getting to it is a pain in removal of a lot of other hardware. I did this with the eBay replacement and it works great. Just took some time to be careful with all the bits and electrical connectors, trim connector, glove box door etc. Just be careful and read Timm’s post for more info.