Subject: 1994 Mitsubishi 3000GT A/C Leaks
Question:

HI, THE AIR CONDITIONER DOES NOT HOLD CHARGE FOR MORE THAN THREE DAYS. I NOTICED THAT THERE IS A LEAK ON THE SUCTION LINE WHICH ATTACHES TO THE FIREWALL EVAPORATOR BILLET BLOCK. I HAVE REPLACED FACTORY O-RINGS, BUT CANNOT GET THE LEAK TO STOP. THE AREA IS RIGHT BEHIND THE BATTERY AT THE FIREWALL. ANY ADVICE AS TO WHY I CANNOT GET THE LEAKING TO STOP. THANKS

Answer: Gus,
Being that A/C lines are aluminum, the can bend, dent, and chip relatively easily. When an o-ring is replaced, the o-ring should first be coated with refrigerant oil. If the o-ring is not seated right or has insufficient lubriation, refrigerant can leak past it.

You may want to confirm to see if you have more than one leak. The most common leaks occur at the front of the car on the condenser. To truly find all leaks, you should use an ultraviolet leak dye. That will help show any obvious leaks when viewed under a blacklight. You can usually find these leak dye kits in auto parts stores.

But the best way to check for for leaks is via a refrigerant sniffer. A sniffer "breathes" in any leaking refrigerant and emits an audible tone when detected. The problem with sniffers is that they are very expensive. The are extremely sensitive and will provide false readings if not used properly. If you can, have a professional A/C repair shop do a full sweep of your A/C lines and components to find exacly where all the leaks are, and to the extent of any damage to the lines that may have caused the leak.
Good luck!