My A/C was working great on my 1987 Mercedes 300D. That is until I power washed the engine bay. Ever since I power washed the engine compartment the A/C compressor will not kick on at all. Does anyone have some suggestions?

Sounds electrical. Check the connection on the compressor and on the low pressure switch on the drier. They might have been knocked loose or shorted.

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Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

On the OM603 there is also a compressor thermal shut down switch on the thermostat housing. Be sure that didn't get unplugged.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Thanks! I have already checked and cleaned the connections on the ac compressor. I haven't checked the thermostat housing yet though. I will let you know what I find.

Check your fuses too! might have had a short from wetness

I usually try to go back to what changed to solve problems, so I assumed that the AC not working had something to do with power washing the engine bay. Yesterday we determined that the problem was the engine temp cut out switch that shuts down the compressor when it senses that the engine is overheating. I'll replace it soon, but for now we just unplugged it and the compressor stays on.
Thanks to all of you for your replies and thanks to everyone who has input on climate control matters so that I can learn more about this system.
Paul H.