An observation and an idea. On my 1985 300D that has been converted to r134 I get air out of the vents that is approximately 30 dF lower than ambient. I noticed the other day when it was raining and about 90 dF outside that I was seeing about a 48 dF drop (getting 42dF out of the vents). I am seriously considering using my windshield washer reservoir/pump and reworking the piping to spray water onto the inlet side of the condenser in front of the radiator to increase the performance of the a/c system. I would not run the pump continuously. My concern would be minerals precipitating out of the water and plugging my condenser as it is evaporated on the coils. I do not use the windshield washer and that 42 dF air sure felt good coming out of the vents.

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Jim