I will try applying power to the compressor to see whta it does.

However I took the ML in to see what the dealer would say - Dealer says compressor is bad and system is contaminated. Must flush the system and replace the compressor - cost $1900.

Just before I took the ML to the dealer I replaced the condenser to compressor hose - I saw no evidence of contamination from a failed compressor. Makes me think I'm not being told the truth. All oil that I've seen from the system is clear and yellow in color. When I turn the compressor by hand it turns smoothly.

If I opt for the dealer to fix the A/C is $1900 is reasonable price?

Is replacement of the compressor on the ML a difficult jobs?