How do you inspect the Air Conditioner?
 

My A/C is not as cold as it used to be. And, it seems to smell like when the A/C is run without "recirculate" on (more humid, or something). Can someone tell me how to tell if the refrigerent is low or how to tell if the recirculate "door" is closing?
Thanks.

Check this link it may help as far as the A/C pressures go.
http://www.peachparts.com/shopforum/ml-gl-g-wagen-r-class-unimog-sprinter/101295-air-conditioning-refrigerant-pressures.html?highlight=a%2Fc

more information please...
 

Thanks for the info on pressures, but I don't know enough about A/C to use that information. I thought that there was a "window" on a part in the system that if there are bubbles showing (or something like that) then, the refrigerant was low?

That right there was. It seems nowadays they don't put a sight glassi n the reciever/dryer any more. It might have something do to with in a system with R134a there would be a few bubbles but the system would still be fully changed, not sure about that though.