Unable to activate A/C compressor

The A/C in our E320 appears locked into the "EC" (economy mode.) Owner's manual says to simply click the EC switch to activate the compressor, but the swtich stays lit and A/C will not produce sufficient
cold air in either auto or manual LO sets. Is there a quick fix or is a trip to service required?
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Think positive! Perhaps you have a slooooooooow leak and all it requires is a little R-134. The compressor will not run after the refrigerant pressure dips below a certain level. It's a precautionary measure so you don't ruin the compressor.
Pre-1993 E320? Then you might(OK, probably) need R-12. Check the label in the engine compartment.
Al wrote:

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It seems to me you got a 1996+ E class... this occurs when there is a fault in the A/C system. I had this occurred a couple of times and it is corrected by changing the evaporator sensor... Apparently some sort of a manufacture defect.
A leak is possible on your car too... however unlikely. Let MB dealer take care of this problem... they know what to do.
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Does the C-class of the same era also suffer from this? My '96/97 C180's aircon will only run if the cabin is dog-roastingly hot, like when it has been left in the sun for a couple of hours. DD
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You have a much simpler system... You should have been able to activate the system by setting to the coldest temp. If not, it is possible that you got a low freon level... have your pressure checked to determine the level of freon (R134).
It seems to me that you might have a low level of freon that your evaporator freezed up therefore unable to provide you cool air... since the evaporator is practically ice block.
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The system (non climate control, just the 'Red/White/Blue' thumbwheels) will not kick in unless the cabin itself is very hot. I'm suspecting a 5 temperature sensor that will cost 500 to replace because of its location.
I have taken it to the a/c specialists twice last summer, but of course by the time I got there, it had started working :-(
I'm waiting for the unseasonably hot weather in SouthEast England to end, and then it's back to the shop. DD
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Then I suggest you let MB dealer take a look at it... I would not trust outside shop to handle this problem... the reason is MB knows the system so they can easily disgnose the problem.
I seriously doubt it is the temperature sensor. It is kind of rare for it to go bad because it is a simple solid state electronic device sensor
You may think you save money by letting 3rd party mechanic working on it... but how often do they work on your particular model as compared to MB dealer? The odd is just terrible. It probably will end up costing you more... let the MB dealer take a look for you..
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