87 300dt
I've done a good bit of troubleshooting on my A.C problem. I know the problem is not the Klima relay (thanks to this board). I thought the problem was the Klima at first and had replaced it. The compressor comes on when the appropriate Klima sockets are shorted.
I've discovered that the compressor will not come on if the system presure is too low. Thankfully, at the last recharge, they added some flourescent dye to the system.
So 11pm, dark garage, and with my Blacklight in hand, I went searching for a leak. I saw nothing in or around the center nor side vents, and nothing on the floor. Then, I opened the bonnet, and found the only glow coming from the indicator on the dryer.
Next, I decided to lift the car and inspect beneath. Bingo! I was sure that this pipe was the culprit!(see pic) So I take the car back to a shop where mechanic say's "this is NOT an A.C. part"! It was glowing brightly and sprayed the surrounding engine parts (especially the bottom of the alternator), but has nothing to do with the A.C. He mentioned that this is a tranny cooler line and the glow is comming from a water pump leak. I use the Mercedes clear coolant and mix it with 50% h2o.
I scratch my head and take his word that the problem is the evaporator, even though his searching with a black light showed no dye-leaks anywhere. Next evening I fill a cup with some of the Mercedes clear coolant and hold my Blacklight nearby, NO GLOW! hummmm!
So, before I rip the dash out, can anyone give some other suggestions or shed some light on this condition?
Thanks,
Freybird

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1987 Blue-grey turbo 300d "The Panzer Vagon"