ac noise under dash

ok the mechanical stuff is no problem for me,the AC I dont know much about.So once in awhile I hear what sounds like pffffft(like pop that has been shaken then opened)from the glove box area when the ac is on,yet it still blows cold.anyone experienced this and what was the remedy.could it be the start of a leak?its a 01 caravan 3.3 and 110k .your help most welcome

That sound is usually indicitive of a leak. The most common place for a leak on your vehicle is from the right front lower condensor area. Look through the bumper on the passenger side at the lower corner of the condensor. If there is an oily residue then it may be leaking there. If not take it to a dealer and have dye injected and to verify a correct charge.

thanks mprtech you were right.Bottom pass side about 8" patch of oil.Going to replace it this weekend,but does that now mean that the evaporator is next to go,or are they better made now?