I believe that some of the newer A/C compressors do not have a clutch that allows them to disengage the compressor from the drive pulley, these compressors can never be completely turned off.

However, they are variable displacement and can vary the displacement to below 5% of maximum allowable displacement. Hitting the EC button should take the compressor down to minimum allowably displacement, which is the closest to off that it can get. Therefore, you should still get a hair of cooling out of it.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record