I used a completely different method of refilling my A/C. I bought a R134A recharge kit with the pressure guage on it from WAL-MART, it had the oil and stop leak in it. I unplugged the low pressure switch and ran a jumper wire to both connectors, unscrewed the cap on the low pressure fill port, I then started the car and with the A/C on high and started filling the system through the low pressure port with refrigerant watching the pressure guage on the refill bottle. Once I got to 45 PSI i called it good, it ended up taking about 2 cans to fill it up. I checked the pressure on it every week or so when I refilled it to make sure none of it leaked out and it has all stayed in with no issues. For about 25 bucks I have been enjoying ice cold air in my car for the last 5 months and it has been working perfectly ever since. I went a whole year after buying the car with no A/C and finally figured I would take a stab at fixing it, I'm glad I did. Good luck.