1998 Audi A4 Quattro. Not sure why, but my heater isn't working? The climate control appears to be working fine. I can get really cold air out with the a/c, but no heat? Any ideas or common fail items that I should look at first? I have let the engine warm up plenty, so it's not that. Any ideas?

 

Search out "heater core" and "thermostat stuck open" to see some likely reasons. Do you get heat at any time? Or is it only cold? That'll help narrow it down.

 

Never get heat. The engine gets hot, so it's not a stuck open thermostat. It just never blows the heat.