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Discussion Starter #1
Well, the time has finally come to start using the A/C... So the other day I turned it on and it works great. Problem is, now it won't shut off!

The only time I can get it not to run is when I press the "O" button on my climate control panel. All other buttons (including the defroster) engage the A/C. Anyone else had this problem or know what's the matter? I have the conversion to the newer refrigerant.

Thanks!
 

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Unplug the low pressure switch wires from the switch (engine OFF) and see if it turns OFF. The switch may be shorted.
 

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Discussion Starter #3
Thanks for the tip! I tried disconnecting the pressure sensor and starting the engine; still on. Then reconnected. Still on.

If I'm not mistaken, you can tell when the pump is running by looking to see if the middle part is spinning, thereby being able to see when it's engaged. The pump is on all the time... wonder if it's gone bad?
 

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What pump? I thought the AC compressor stays on....
What controls the voltage to the AC compressor is the N6 relay. Try unplugging it (it's behind the battery; a large black relay)
 

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Discussion Starter #5
What pump? I thought the AC compressor stays on....
What controls the voltage to the AC compressor is the N6 relay. Try unplugging it (it's behind the battery; a large black relay)
I meant the compressor... sorry. I thought it had a clutch that engaged and disengaged it. I know that it drains a little bit of power when I turn on the A/C anyway...

Do you mean the large box in the front of that compartment (the one by the MAS relay) or the one in the back? I haven't been able to find a parts listing for that relay to see what it looks like.
 

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Way in the back; almost against the firewall on the passenger side, behind the battery. It is difficult to get to and even more difficult to pull out.
 

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Discussion Starter #7
I was afraid of that! Ok, I'll go check it out...
 

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Mercedes Benz forever. :)
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Discussion Starter #8
Okay Sergio, so I went back and disconnected that relay and started the car... other than the SRS light staying on, nothing changed. The darn thing sure is putting out cold air though! Just would be nice to be able to shut it off once in a while...

Guess I'm left with taking it down to my A/C guy and have him take a look!
 

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The compressor has a 3 wire connector plugged into it. Unplug it. Maybe those wires are shorted? When you disconnect this connector, the AC compressor WILL NOT STAY ON.
Good luck!
 
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