Preparation For Leak Testing

Connect manifold gauge set to air conditioning system. Ensure low-side and high-side gauge set valves are closed. Check system pressure. It should be at least 50 psi (3.5 kg/cm² ). If system is empty, evacuate A/C system and apply 28 in. Hg of vacuum. If system holds vacuum for 15 minutes there most likely are no leaks present. If low, add just enough refrigerant (about 10 ounces) to bring system to 50 psi (3.5 kg/cm² ).

Ensure all joints, connections, and fittings are free of oil dirt and other contaminants. Using a refrigerant leak detector, check all refrigerant line connections for leaks. Check condenser and compressor seal area.

Start engine and allow to idle. Operate A/C system for about 5 minutes. Set A/C controls to outside air, and high blower speed. Turn A/C on, and open vehicle windows. Turn engine off and wait 2-7 minutes. Refrigerant is heavier than air. Always check for leaks at bottom of refrigerant lines and components. Refrigerant oil will leak with refrigerant. Visually check all connections and compressor clutch area for oil stains. If compressor shaft seal is leaking, a fresh oil streak will normally be seen on underside of hood, above compressor clutch.

Always perform leak testing after A/C service. Move refrigerant leak detector slowly to check for leaks, as leaks will not be detected if leak testing is performed too quickly.