So my old 1999 ram has r134a in it. After being parked all winter its always a little low on refrigerant, not empty but not blowing cold. Are there any A/C experts out there that can give me some advice on this. We put dye in the system but can't find the leak. Once recharged it works great all summer and I was thinking of converting so I could just top up when needed instead of having to book it into an A/C shop every spring.