I have a 2003 T & C that recently started having A/C problems. It blows really cold air for about 15 or 20 minutes, then it turns warm. I bought a recharge kit and the gauge showed it to be at 25 psi at 80* ambient. I recharged it to 40 psi and let it run for a half hour like the instructions said. When I went out and checked, it was blowing warm air again and when I put the gauge on the low side, it pegged the gauge at 150 psi. What has happened?