Just curious if anyone knows at what point low the pressure switch dis-ables the compressor? Had my system converted 2 years ago and cooling was o.k. for 2 L.A. summers but this spring I noticed the compressor not kicking in. After searching archives here I learned how to jump the switch to check compressor. I then added one can of r134 and a leak sealer/oil charge tune-up deal. Hard to get a decent reading with one of those low side gauges but on a warm day the vent temp at idle gets to about 50 or 55. Yesterday it was in the 90's here and driving in stop and go the vent was between 60 and 70. A bit cooler today and the comp. was cycling a bit, vent temp on freeway between 50-55. This is a 240 so capacity (if it were R12) is 46 or 48 ounces, can't recall which. I have a feeling I'm still a bit on the low side but don't want to overcharge. I'd appreciate any advice on the matter.
Oh, I noticed also yesterday when I tapped on the expansion valve the vent temp dropped a couple of degrees.

As always, advice is greatly appreciated.

thanks
Kirk S.