I had my high pressure switch/sensor changed last year....Have not driven the car in over a month 1/2...started it up and the a/c was not working....thought it was maybe the same issue...happened for what ever reason to remove the black cap/cover off of the high side and as soon as I did air started blowing out.......they do make a schrader valve replacement but inside mine was a black ball......went to AZ and purchased a 12 dollar set of fittings and switched it out...two cans of coolant and we are back in the cold.....just thought I'd share...
Will
Will