A/C help w124. Steve Brotherton?
 

Steve, thanks for your excellent article on a/c diagnostics. Car is a 1988 300TE. When purchased in Feb 04 I was told the pushbutton controller didnt function properly because it only put out heat when the temp control wheel was set to the maximum setting (past the point where it "clicks"). As the weather warmed, the a/c set on maximum cool only (also because i was told the pushbutton didnt work) stopped cooling from time to time until I cycled the engine. Usually cut out on the highway, not in town. So, I (indy shop actually) have replaced the klima relay and the receiver drier, recharged the freon, and now most recently replaced the pushbutton control with a reman from programa. Problem is, the original symptom of no heat except in max setting persists. I drove the car for 40 minutes yesterday on cool settings and the blower never moved off of maximum setting as I assumed it would when correct cabin temp was reached. I am frankly at my wits end and concerned my shop is simply at the point of replacing parts without really understanding the problem. Any advice would be appreciated.