The A/C on my '93 S-Class (400SEL) had decided it wanted to conk out here in the middle of July. I rarely use A/C, but have wanted to use it lately. I am wondering if lack of use may have been the problem?

Anyway, it was working fine, then one day it wouldn't work until after on for about 10 minutes. Now when I turn it on the compressor will make a "groaning / squawking" noise for about 3 seconds, then it will click off and then of course only hot air blows out of the vents.

Does it sound like it is low on gas (preventing the compressor from kicking on and staying on), or has the compressor conked out? I have the car for sale, but will sell easier with working A/C. I have reduced the price of the car by $500 down to $3000, which I think is more than generous, but still. I think even if it needs a new compressor, it will not be over $500, if it does, then Lord help the W140 owner.

The A/C evaporator, heater core, condenser and blower motor were replaced two years ago to the tune of $3300 to get cold A/C. Now this happens. I am not sure if the compressor has ever been replaced or not, I will need to look through the service records - which there are tons of.

Thanks in advance.