Your post has been moved to the regular part of the Grand Prix forum. Since you have an Intrigue with the 3800 we will allow this post here and at Olds Intrigue since this is a shared forum. Some answers were provided at the Olds Intrigue forum at link below.
http://www.automotiveforums.com/vbul...d.php?t=720776
The low side port should be located at the firewall. The high side by the accumulator located at the driver's side front of car. As long as it is not illegal in your state any R134a recharge kit you can get at auto parts stores will allow you to test refrigerant charge, mainly at the low side port. The connection point to the ports are standardized for GM R134a systems. Although you should take it to a Pro you can do certain things DIY like check the high and low side pressure. The proper readings will depend on factors such as ambient temperature. However, accurate/quality gauges should be used. The cheapy DIY kits with gauge at the auto parts stores are not very accurate.
What are your symptoms where you feel the A/C system should be recharged? If you have a leak then a vacuum check should be run or leak detection test. Leaks should be located and repaired first before attempting a recharge.
Recharge A/C '99 Intrigue (3.8L)
