84 733i heater blower problem

Strange heater blower problem with 84 733 I. If I leave the fan control switch on in any position things work fine, shutting off the car restarting etc. if I shut the fan switch off and turn it back on all heater controls become inactive except for the defrost switch. I will see some dim light's on active controls and can hear occasional clicking IE relay clicking until eventually for no reason everything goes back to normal. I have not searched this problem too much as everything usually comes back on. Any troubleshooting hints would be greatly appreciated.
PS acts like either a bad relay or main power feed, electronic troubleshooting I have no problems with just have limited resource information. If anybody has any stereo problems, that's what I do for living,ie repair car stereos.
Thanks Jeff B.

The best source that I've seen for BMW heater info is "Sean & Johan's" site, two guys from the Netherlands. Unfortunately, I've lost my bookmarks and don't have it handy. Go to www.roadfly.org and you'll find it without much trouble.

http://www.bimmerboard.com/forums/posts/12793

Check this link .

Thank you everybody for the responses my heater control now functions normally...... Jeff B. P.S. I am a stereo technician any questions feel free to ask

Had the same problem with my '84 733 for several years. Replacing the controls (thumb wheel unit and push button contol) did not help. I think it's a relay because I hear a clicking noise under the kick panel on the driver's side while the green light is flickering. Just joined the forum and haven't had a chance to investigate the links in other replies. Did you have any luck solving the problem? John H.