I have a 93 100 cs that I love. Made a big mistake though and let a dealer ugrade a tired Bose system to Alpine Satellite Radio. My electrical and computer systems, the heater, on flashing error codes have been a problem ever since. Radio guy, of course, said it ws not his fault.I lost my owner's manual so I am at a loss as to some of the flashing icon codes. What is an circle with a xmall square box at the top? How about the letters MPG with a circle arounid them? Also the heater is not putting out any heat. The blower works fine and the heater core ws replaced last year (BIG bucks). Entry ande exit hoses are hot so coolant is passing through. Is there door in the air plenum that moves air from heat to A/C that may be stuck?

Finally, the automatic temp control unit and temperature reaout above the sterring wheel are unlit. They can be read in daylight or with a light. Is this part of the problem.

Otherwise, everything is fine!

Thanks for your help.

 

I'm not sure which warning's you're seeing, it sounds like the one you described is a warning about lights. I did a quick google on Audi warning lights and got this. http://net.jasonpearce.com/chronicle/audiwarnings.html
Maybe it'll help. The warning lights have stayed fairly consistent over the years, I think newer Audi's just have some newer ones.

As for the heat, I do think there is a door or panel that opens and closes to allow the hot air from the heater core to pass into the passenger compartment, but someone else who's worked on it or knows better can confirm this.

For instrumentation, it could be a bulb in the panel or a fuse that's blown.