Leak Tests

R-134a systems require the use of special service equipment designed specifically for R-134a systems. R-12 servicing equipment cannot be used on R-134a systems.


Testing the refrigerant system for leaks is one of the most important phases of troubleshooting. One or more of the methods outlined will prove useful in detecting leaks or checking connections if service work is performed. Before beginning any leak test, attach a manifold gauge set and note pressure. If little or no pressure is indicated, a partial charge must be installed. Check all connections, compressor head gasket, oil filler plug and compressor shaft seal for leaks.

ELECTRONIC LEAK DETECTORS

There are a number of electronic leak detectors available to perform leak tests. Refer to operating instructions for the unit being used and observe these general procedures:
1. Move the detector probe one inch per second in areas of suspected leaks.
2. Position the probe below the test point, as refrigerant gas is heavier than air.
3. Be sure to check service access gauge port valve fittings, particularly when valve caps are missing, as dirt accumulations can destroy the sealing area of valve core when manifold gauge set is attached. Replace missing valve caps after cleaning valve core area. Valve caps should only be finger tightened. Using pliers to tighten valve caps may distort sealing surface of valve.
4. Check for leaks in manifold gauge set and hoses, as well as the rest of the system.

FLAME-TYPE (HALIDE) LEAK DETECTORS

When using flame-type detectors, avoid inhaling fumes produced by burning refrigerant. Do not use this type detector where concentrations of combustible or explosive gases, dusts or vapors may exist.
1. Adjust detector flame as low as possible to obtain maximum sensitivity. Be sure copper element is cherry red and not burned away. The flame will be almost colorless.
2. Slowly move detector along areas of suspected leaks. A slight leak will cause the flame to change to a bright yellow-green color. A significant leak will be indicated by a brilliant blue flame. Position detector under areas being tested as refrigerant gas is heavier than air. The presence of dust in the pickup hose may cause a change in the color of the flame. If not recognized, a false diagnosis could be made. Store leak detector in a clean place and ensure hose is free of dust before leak testing.
3. Check for leaks in the manifold gauge set and hoses, as well as the rest of the system.
4. Use a small fan to ventilate areas where the leak detector indicates refrigerant constantly. These areas are contaminated with refrigerant and must be ventilated before leak can be pinpointed.

FLUID LEAK DETECTORS

Apply leak detector solution around joints to be tested. A cluster of bubbles will form immediately if there is a leak. A white foam that forms after a short while will indicate an extremely small leak. In some confined areas such as sections of the evaporator and condenser, electronic leak detectors will be more useful.