this isn't the first time this happened on me. what happened is i guess when i turn my 07 coupe off, i tend to leave the a/c on and just turn it off, then when i start it again, the a/c is already starting to blow and when i turn on the engine, the small valve near the front just pops off causing me to lose all my refrigerant. I have no idea why it does that and i'm afraid to take it to the dealer because my car isn't under warranty. the first time that happened, i just had the refrigerant replaced, the 2nd time it happened which was today, i had a mechanic take a look at it but he couldn't find anything either. he just recovered all my refrigerant and replaced it i guess. while he was doing this, my service engine soon light came on and i have no idea how to fix that. if anyone knows how to prevent the popping of the a/c valve that shoots green coolant on my hood, that would be great. thanks to all.