Have a shop do it,they can add dye in with the freon to detect leaks. take it back a few days later and they will use a uv light to find where the leaks may be.It is possible but very remote that your refridgerant is just old and need to be recycled but more likely at that age there is a leak.

out of all the jeeps in this town the d**n gremlin had to invade mine

I've done so much,with so little for so long i can practicly do anything with nothing