I surely would have had the freon checked in the system first. Heck the dealer I worked at we got like 1.5 to suck all the freon out which tells how much is in it. Then it also included us adding dye and looking for leaks after we filled the system with the proper amount of freon. The cust price was about $139. for that. If we found no leaks then we had the cust come back in a week or two and we checked to see if we could see any dye and find the slow leak. To replace the shrader valve takes about 20 seconds after the freon is pulled out. Cant say we did not tell you as after what J-body and I said I would have had the system charge checked. I just hope the schrader valve is not your only leak. Ron