A/C blower not working 88 928 s4

just started happening. ac works great but now when i push ac button , nothing happens and blower switch does not work. if i leave it on for 10 minutes it comes on and works perfectly.what do i look for, thanks so much, john volak

Check Fuse #17 for traces of overheating - if it appears to have been hot, clean the connectors and the fuse connectors. Actually, cleaning is a good idea in any case...

If the fuse isn't the problem, try the blower on AC. If it doesn't work, move the system lever to DEFROST. If the blower now works, the problem may well be Relay X, the Fresh Air Blower Relay.

If it appears to be faulty/intermittent, try swapping it with Relay VIII, the Defrost Relay. If the relay is faulty, replacements are relatively cheap.