My A/C didn't work when I needed it to this warm season. The compressor wouldn't turn on. I put a 13 oz can to it and it registered at 0 psi. Pulled the trigger a bit, and it went up to 25 psi pretty quickly. I tried the A/C and the compressor kicked on, but the air still wasn't cold. I put some in a little at a time, checking the A/C temp as I went, and it never blew cold---all the way up to 46 psi. There is still liquid in the can.
I used this can initially to check a Rav4 I've since sold. It registered at 60 psi on the lowside with this can. When I took the Rav to the mechanic becuase I thought it was overcharged, I found out it was in fact, a pound and a half short of freon.
So I think this gauge on the can is about what you could expect out of spending $15.95.
So my question is: HOW LOW WOULD THE SYSTEM HAVE TO BE TO KEEP THE COMPRESSOR FROM COMING ON? MORE THAN A POUND?
If so, I'm just gonna put this can in.