DeVille, Eldorado, Seville 1999-2005

Testing The System


Leak Testing

Fluorescent Dye Leak Detection

Fluorescent dye will assist in locating any leaks in the A/C system.

Observe the following:

J41447 is the only dye approved by General Motors. Not all of the R-134a dyes are compatible with PAG oil. Some dyes decrease the oil viscosity or chemically react with the oil.
PAG oil is water soluble. Condensation may form on the refrigerant lines or on the evaporator core. This condensation may wash the PAG oil or the leak dye off of the line or off the core and out through the condensation drain. Condensation may make some leaks harder to find using the dye detector. Fluorescence at the drain opening indicates a core leak.
R-134a tracer dye requires time in order to work. Depending upon the leak rate, a leak may not become visible for between 15 minutes and 7 days.
The dye, when mixed with the PAG oil, remains detectable in the system for 2 years. Do not double the system using dye. This may cause reliability problems. Use only a 0.25 oz charge.
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. Use the leak detection lamp in the following areas:

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 The sealing cap is the primary seal for the service ports.

To prevent false diagnosis in the future, thoroughly clean the residual dye from any area where leaks were found. Use a rag and an approved fluorescent dye cleaner.

Halogen Leak Detector

A halogen leak detector is the most useful tool for locating refrigerant leaks. Tool J39400 provides an audible signal which increases in frequency as the unit detects R-134a. Follow the instructions included with the unit in order to properly calibrate the instrument. Use the detector in the proper setting for the type of tested refrigerant. Set the detector gas switch to R-134a prior to use.

The most common leaks occur at the refrigerant fittings or connections. The leaks may be the result of any of the following conditions:

Improper torque
Damaged O-rings
Lack of lubricant on the O-rings
Dirt or debris across the O-ring
Small pieces of lint from cotton gloves or shop cloths on the O-ring

In order to successfully use tool J39400 or any other electronic leak detector, maintain a proper scan rate. Carefully follow the manufacturer's instructions regarding calibration, operation, and maintenance.

During testing, completely circle each joint using the probe at a rate of at 51 mm (1-2 in) per second. Place the tip of the probe less than 6 mm (0.25 in) away from the surface. Do not block the probe tip air intake. A leak exists when the audible tone changes from a steady 1-2 clicks per second to a continuous alarm. Frequently adjust the balance knob in order to maintain the rate of 1-2 clicks per second.

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 0.45 kg (1 lb) of refrigerant in the A/C refrigeration system in order to perform a leak test.

Halogen leak detectors are sensitive to the following items:

Windshield washing solutions
Many solvents and cleaners
Some adhesives used in the vehicle

Clean and dry all surfaces in order to prevent a false warning. Liquids will damage the detector.

  1. Use this procedure in order to test the following components:
    Follow a continuous path in order to ensure that you will not miss any possible leaks. Test all areas of the system for leaks.

    The evaporator inlet
    The evaporator outlet
    The accumulator inlet
    The accumulator outlet
    The condenser inlet
    The condenser outlet
    All brazed joints
    All welded joints
    The compressor rear head
    The housing joints