Climate control blowing fuses
 

Hi all;
I have posted before about this condition on my 89 300SE and have gotten many helpful suggestions.To recap my problem... When I turn on the air conditioning,it blows a fuse immediately.This is what I have done in the way of trouble shooting so far. Disconnected the aux.fan ... still blows.Neutralized all the blower speed buttons so it wouldn't come on .. still blows. Last night I discovered that if I select vent only ( the first button to the left of off )the blower will run and the fuse doesn't blow.Is this a key clue to my problem? Is there a relay for the compressor that may be bad? Help!!