Cobalt 2006-2008, G5 2007

Leak Testing


Before beginning this procedure, refer to the Precautions at the beginning of this section. Only a MVAC-trained, EPA-certified, automotive technician should service the A/C system or its components.

General Motors vehicles are currently manufactured with fluorescent dye installed directly into the Air Conditioning (A/C) system.

The fluorescent dye mixes and flows with the PAG oil throughout the refrigerant system
Verifying some passive leaks may require using the Halogen Leak Detector J 39400-A, even though the A/C system contains fluorescent dye
The only time that adding additional fluorescent dye is required is after flushing the A/C system
Fluorescent dye will assist in locating any leaks in the A/C system

PAG oil is water soluble.

Condensation on the evaporator core or the refrigerant lines may wash the PAG oil and fluorescent dye away from the actual leak. Condensation may also carry dye through the HVAC module drain
Leaks in the A/C system will be indicated in a light green or yellow color when using the leak detection lamp

  1. Use the leak detection lamp in the following areas:
    To prevent false diagnosis in the future, thoroughly clean the residual dye from any area where leaks were found. Use a clean rag and the approved J 43872.

    All fittings or connections that use seal washers or O-rings
    All of the A/C components
    The A/C compressor shaft seal
    The A/C hoses and pressure switches
    The HVAC module drain tube, if the evaporator core is suspected of leaking
    The service port sealing caps as the sealing cap is the primary seal for the service ports

  3. If necessary, inject fluorescent dye into the A/C system that is approved by General Motors:
    Not all of the fluorescent dyes are compatible with PAG oil. Some types of dye decrease the oil viscosity or may chemically react with the oil.

    R-134A leak detection dye requires time to work. Depending upon the leak rate, a leak may not become visible for between 15 minutes and 7 days.

    Do NOT overcharge the A/C system with dye. Use only one 0.25 oz (7.39 ml) charge.

    J 41447 can be poured directly into a removed A/C component
    J 46297-12 is injected into the low side port using J 46297


Halogen Leak Detector

Do not operate the detector in a combustible atmosphere since its sensor operates at high temperatures or personal injury and/or damage to the equipment may result.

Ensure that the vehicle has at least 1 lb. (0.45 kg) of refrigerant in the A/C refrigeration system in order to perform a leak test.

Halogen leak detectors are sensitive to windshield washing solutions, many solvents and cleaners, and some adhesives used in the vehicle.

Clean and dry all surfaces in order to prevent a false warning. Liquids will damage the detector
Follow a continuous path in order to ensure that you will not miss any possible leaks. Test all areas of the system for leaks
Follow the instructions supplied with the Halogen Leak Detector J 39400-A