Can anyone tell me why my 89 300se's ac works one time you start the car and the next it may not? I have had it checked for leaks, it has a new blower, and has be recently charged. Friday it only blew warm air. Saturday it was back in the shop that charged it before and it blew ice cold for over an hour and never did quit. Then, I took it to the grocery store and it worked fine until I came out to go home and then it blew only warm air. It sounds like to me like a loose connection. Larry Bible suggested that it may be something electrical and I can agree. Has anyone ever had this problem? Any suggestions?

Had that problem with my 89 190e. Tracked it down to a short on the circuit board of the climate control unit. Looked like something shorted out on test point 2.

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89 190E
2.6L
Arctic white
Grey leather
Sunroof
Pirelli P400 rubber
Smoked corners

Have you hosed down the engine recently?

I did a "power wash" on the engine compartment one evening only to experience the same "on-again-off-again" A/C for nearly a week.

I agree, it's electrical...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

Would it be better to just try and replace the climate control board or try to fix the short. When the ac comes on, it does blow extremely cold, due to the recent charge. So, I feel the system itself outside is working good. Any suggestions on what I should do to resolve the problem?