I have a 91 300E with 170K that was recently working fine with AC vents blowing correctly. I decided to turn on the Defrost mode to see if it worked (and it did...got very hot,very fast!) but when I switched it back to normal AC dashboard only operation, it was still blowing strong out of the defrost vents and front force was noticeably lower than before. It is nice and cold but is still like that today. What should I check and any advice on how to fix...scared of the answer Thanks