i have a 2000 chrysler grand voyager, the a/c wasn't blowing cold and the low-pressure line was reading 75 psi with the engine on and a/c set to max+recirc, 70 psi with the engine turned off- took it to an a/c place and the technician said that the compressor had too much shaft play. so we replaced the compressor, filter/drier and expansion valve. tried to charge the system but after a can and a half of freon, the pressure gauge was bouncing around, sometimes reading a max of 15 psi. how much pressure/many cans of R134a do i need to pump into the system before the pressure stabilizes and the air starts blowing cold?

 

look on the blue label under the hood see which system u have single or duel air it will tell u how many LBS u will need 1 small can 12oz is 1 lb

 

i'll do that. i know it'll be 32-48oz, but my main concern is when i was charging it, the gauge was jumping around, usually after disconnecting the gauge/nozzle from the a/c line then reconnecting it, would read 15 psi then go back down when starting to charge again. so i'm wondering if this is normal or if i should see a steady increase in the pressure.. and if so does it start right away or after a certain ammount of freon has been put it

 

U cant go by the gauge when adding it because u are adding plus what U are reading off of the already pressure in the system.

 

thank you, i think i understand where you're going. in a nutt shell i can't expect to see a rapid increase in pressure while charging and will only see the true pressure after releasing the trigger, disconnecting the charging line then reconnecting it? 15 psi was the last measurement i had before i stopped charging for fear that i didn't connect something tight enough(going to recheck the expansion valve retrainer plate) but how much do i actually want? do i go off of the 25-45 psi that's on the gauge? or should i consult the chilton's manual? or an auto part's store? thank you again for your help