Pontiac Repair: Adding Refrigerant, pontiac firebird, metal oil

Question
I have a 1996 Pontiac firebird that I am trying to add refrigerant to.  I was told the low side port is the small capped nozzle on the "it looks like a metal oil filter to me" and I tried to add to it yesterday and it did nothing - what am I doing wrong?

Answer
Hi Kelli:

those add refrig kits you can only hook them up to the lo side port which is right where you said it is. If the system will not take a charge try putting th can in a bucket of hot water and add it that way. Ther may be a partial charge in the car already and the pressure in the system of the car is higher then the pressure in the can so it wil not charge. Start the car and turn the a/c on. once the a/c system starts up it should take the charge Be careful NOT to overchage the system!
Good luck :)