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Mercedes Benz w201
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Discussion Starter · #1 ·
Hello,
I have a Mercedes w201 190 2.5 diesel.As the hot days are coming,I checked the A/C system of the car.When I turn on the a/c it starts working fine but after a few minutes it cuts off,and never turns on again.I checked the Freon(mine is on R12)and it's reading fine.When the A/C was working it cools properly so I think the compressor is doing his work when it's working.I think it's something from electrics.
I take off the relay (near the battery) for a few seconds and when I put it back the A/C starts again(reset),not for too long.and I repeted this for few times but it stills shut off after a few minutes.
Does any one experience this problem,from where I have to start checking the electric components?
Thanks
 

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80 450sl 83 300td
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check and see if the belt is slipping, it has a speed sensor in the rear of the compressor if the belt slips it shuts off the compressor till it gets a reset.
 

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Mercedes Benz w201
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Discussion Starter · #3 ·
Hi Thanks,
I checked the V Belt and is not slipping, Is there a way how I can check the speed sensor on the comporessor?
Like brige the wires to see if this is shutting the compressor?
I am thinking that it is the relay that I have near the battery compartment,(as I was reading other threads)But I do not know how to check it?
 

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I have the same problem

My A/C compressor drops off shortly after the car starts up as well. I also have to reset the the A/C system by turning off the ignition and restarting. Question, if the high pressure switch (dryer location) is activated and stops the compressor, does it require a ignition reset as well? or will the compressor reingage, when the pressure drops? My A/C unit was recharged and converted over to 134A refrigerant. The problem appeared after conversion. Could it be the speed sensors? A/C compressor/ diesel engine speed sensor?. Engine belts are tight, no slippage!. A/C auxilary fan unit is running properly!. any help would be appreciated
 

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'01 SLK230,'93 190E 2.3, 1971 LS5 Corvette Convertible
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2,227 Posts
RedFar said:
Hello,
I have a Mercedes w201 190 2.5 diesel.As the hot days are coming,I checked the A/C system of the car.When I turn on the a/c it starts working fine but after a few minutes it cuts off,and never turns on again.I checked the Freon(mine is on R12)and it's reading fine.When the A/C was working it cools properly so I think the compressor is doing his work when it's working.I think it's something from electrics.
I take off the relay (near the battery) for a few seconds and when I put it back the A/C starts again(reset),not for too long.and I repeted this for few times but it stills shut off after a few minutes.
Does any one experience this problem,from where I have to start checking the electric components?
Thanks
Make sure the auxillary fan is operating. If it isn't, the high pressure switch on the receiver/drier will disengage the compressor until the pressure equalizes.
 

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2008 Outback 2.5 XT, 2012 CNG Civic
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slk230red said:
Make sure the auxillary fan is operating. If it isn't, the high pressure switch on the receiver/drier will disengage the compressor until the pressure equalizes.
I agree with slk230red. Make sure the aux fan runs - it's easy to check. The fuse for the fan might be on its way out.
 

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1993 Mercedes Benz 190E 2.3
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While this problem seems to be pretty common, a friend of mine who is a mechanic says these Mercedes could have something called a "wide-open throttle sensor", I'm not sure what it is, but he sais that could be a source of the problem? But, if any of you know what that sensor is, please post it and also include how it corresponds with the compressor. Thanks, Mike
 

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'01 SLK230,'93 190E 2.3, 1971 LS5 Corvette Convertible
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1993MB190E said:
While this problem seems to be pretty common, a friend of mine who is a mechanic says these Mercedes could have something called a "wide-open throttle sensor", I'm not sure what it is, but he sais that could be a source of the problem? But, if any of you know what that sensor is, please post it and also include how it corresponds with the compressor. Thanks, Mike
If it were me, I would connect a set of A/C gauges to the compressor and monitor what is happening on the high side of the A/C system when the compressor cuts off.
Normally, if the car is cold when you turn on the A/C, the compressor will operate and the auxillary fan will turn on when the high pressure gets to a certain point, and the pressure will drop as air flows across the condensor.
If the pressure is in range when the compressor shuts off, you may want to check the high pressure cut off switch on the drier/receiver. If it is opening too soon under lower than normal shut off pressure, you could short out the two leads connected to it and see if the compressor stays on. The problem on my 190 was a blown auxillary fan fuse. During my troubleshooting, I shorted out the leads on the high pressure switch and the compressor would continue to operate.

So, check out the basics before you look at a "wide open throttle sensor", if our cars so indeed have one. I don't ever remember my 190 compressor cutting out if I floor it.

Check:
1. Auxillary fan operation when A/C is on.....if okay, then
2. High pressure switch on drier/receiver...remember- if the switch opens too soon, the compressor will shut off. I have only experienced this particular problem once. I had to evacuate the system, replace the drier/receiver with new high pressure switch, vacuum system and refill with R12.
 
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