A/C Refrigerant Leak

[Chuck Lemberg]

Two summers ago, I replaced every A/C component on my 1996 Dodge Intrepid (3.5L) – You may be wondering why I put so much money into such an old auto. I did it because I really like the car. It has everything I want in a car and nose of the modern features that can lead to additional maintenance costs. SOME examples: no TPMS, no lane departure, no turn signal indicators in the side-view mirrors, no electronic parking brake, etc. Besides, I can usually absorb the costs for maintaining it but couldn’t afford a car payment.

I added the specified amount of oil to each component per the factory service manual. I vacuumed it down (with a manifold gauge set) and charged it with the specified amount of r-134a (using a scale to weigh it). The vent temp was 54 degrees on a day with temperatures in the upper 80’s and high humidity. I was pleased.

Unfortunately, it lasted only about a week. As it was near the end of the season, I decide to put off any attempts at repair until this past summer (even though it would limit the defrost capability in the winter). When I vacuumed down the system, I applied vacuum for an hour and a half. I then let it sit for more than three hours. I had no drop in vacuum. So I charged it back up with satisfactory results. That didn’t last even a day.

I bought a refrigerant sniffer but couldn’t detect any leaks. I will likely buy dye to put into the system on my next attempt, along with the glasses and light needed.

But I am completely baffled. What would cause the A/C system to hold vacuum but then leak refrigerant when charged (i.e., pressurized)? NOTE: the shrader valves are also new.

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