Good Morning to all;

Yesterday, after leaving my 1991 300E parked all day, the AC never came on upon starting. It had worked fine up until yesterday morning. Now this happened intermittently last year and just as I was at the end of my rope, it started working again and has been for the last 7 months-until yesterday.
Last year, if I would hit the AC off button and then turn it on, I would sometimes hear the vents operate (sounds like it opens or shuts) and the AC would work along with the air recirculating switch. Sometimes back then, as it is doing now, the AC switches don't do anything, the air recirculating switch is doing nothing, and hot air blows out the windshield defroster vents and I can't turn it off.

Any clues?

Nick