I want to know why my car goes through alot of freon in a year? on 1999 Chevrolet Prizm

I have notice that I have to put freon in my car a few times a year.I just finished putting freon in my car and I posted it in my phone calendar to keep track of it.I also want to know if the low port where you put the freon into suppose to have a cover or some kind of top to keep it from leaking.

by in Orlando, FL on April 12, 2013
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2 answers
ANSWER by , April 12, 2013
It has a leak. The valves should be capped to keep dirt from getting in. Blow out with compressed air before hooking up hoses your charging with. To find leak , maybe charge with dye and use ultra-violet light to find it.
ANSWER by , April 13, 2013
I agree with ziptie your evaporator core could be leaking