Originally Posted by fast_eddy
Im not asking about freeze12, r12, r134a, or the hose. Everything I have will work with my current r12 system. My only question is if anyone has experience using the kind of manifold gauge pictured in the link with a can tapping r12 hose. Of course it can be done without a gauge... But I sure would like to know how much pressure is in the system first, and as stated I don't want to buy the full manifold gauge set.
if you need to know then buy a proper gauge set so you can check the low side and high side... Harbor Freight sells a nice set and they are not expensive...
you dont really need a gauge to fill the system unless you want to check the variation between the high side and low side... this will tell you if the compressor is worn or the screen is partially clogged...not much more
to fill it so it operates to the COLDEST temps fill it just until the compressor does NOT cycle when your cruising down the highway around 55mph... it will cycle when you hit the coldest temps around 35° or just under... but if you can sustain 40° and the compressor not cycle at cruise speed its full enough...
If it isnt cycling not (not low ) do NOT add more... you can Hydraulic the pump and snap the belts and/or explode the compressor...
Freon gets the COLDEST at the LOWEST low side pressure and not cycle the pump... more presure does NOT = colder it ='s warmer... its opposite