GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1998 🢒 Park Avenue 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 Leak Testing

Refrigerant Leak Testing

Caution: 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.

Perform a refrigerant leak test on the system whenever you suspect a leak. Also perform a refrigerant leak test after a service operation which disturbs any of the following items:

    • The components
    • The lines
    • The connections

Ensure that the vehicle has at least 0.4536 kg (1 lb) of refrigerant in the refrigeration system in order to perform a leak test.

Electronic Halogen Leak Detector

Important: Halogen leak detectors are sensitive to the following items:

   • Windshield washing solutions
   • Many solvents and cleaners
   • Some adhesives used in the vehicle
Ensure that the surfaces are clean in order to prevent a false warning. Ensure that the surfaces are dry. Liquids will damage the detector.

Use this procedure in order to test the following components:

    • 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

Object Number: 82106 Size: SH

Important: Follow a continuous path in order to ensure that you will not miss any possible leaks. Test all areas of the system for leaks.

This type of leak detector is the most useful tool to locate refrigerant leaks. The J 39400 is a small unit that operates on 12 volts DC. The J 39400 provides an audible signal that 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 O-rings
    • Dirt/debris across the O-ring

Object Number: 82107 Size: SH

Maintain a proper scan rate in order to successfully use the J 39400 or any other electronic leak detector. Carefully follow the manufacturer's instructions regarding the following items:

    • Calibration
    • Operation
    • Maintenance

In order to test for leaks, complete the following steps:

  1. Completely circle each joint with the probe at a rate of at 51 mm (1-2 in) per second.
  2. Place the tip of the probe as close as possible to the surface, but no more than 6 mm (0.25 in) away. Do not block the probe tip air intake.
  3. A leak exists when the audible tone goes from a steady 1-2 clicks per second to a continuous alarm.
  4. Frequently adjust the balance knob in order to maintain the rate of 1-2 clicks per second.

Object Number: 82101 Size: SH

Fluorescent Leak Detector

Tools Required

    • J 41447 Fluorescent Tracer Dye
    •  J 41436-1 R-134a A/C Tracer Dye Injector
    • J 28428-E High Intensity Black Light

Important: 

   • J 41447 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 on the refrigerant lines or the evaporator core may wash the PAG oil. Condensation may leak dye off the line or off the core and out 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 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 with dye. This may cause reliability problems. Use only the ¼ ounce charge.

If you know that the system has lost charge and you can not find a leak with the J 41436-1 .

Service Ports/Access Valves

The primary seal for the service ports is a sealing cap. The cap contains an O-ring or gasket that provides a leak-free seal. The following conditions will cause a refrigerant loss:

    • A loose cap
    • A missing cap
    • An incorrect cap

Evaporator Core

One of the most difficult leaks to find is in the evaporator core. Complete the following steps in order to test the core for leaks:

  1. Turn the blower on HI for 15 or more seconds. Turn the blower off.
  2. Wait 10 minutes.
  3. Remove the HVAC filter access door and the HVAC filters.
  4. Insert the leak detector probe into the opening. Try to get as close to the evaporator as possible.
  5. A solid alarm on the detector indicates a leak.

Compressor Block Fitting and Shaft Seal
  1. Blow compressed air into the following locations for at least 15 seconds:
    2. • Behind the compressor clutch/pulley
    • In front of the compressor clutch/pulley
  2. Wait 1-2 minutes.
  3. Probe the area in front of the pulley.
  4. A solid alarm on the detector indicates a leak.