Caution: Avoid breathing A/C Refrigerant 134a (R-134a) and lubricant vapor or mist. Exposure may irritate eyes, nose, and throat. To remove R-134a from the A/C system, use service equipment certified to meet the requirements of SAE J2210 (R-134a recycling equipment). If accidental discharge occurs, ventilate work area before resuming service. Additional health and safety information may be obtained from refrigerant and lubricant manufacturers.

Caution: Take care to prevent personal injury which could occur due to touching a hot engine when testing. Tests should be done with the engine "Off" and as cool as possible. Do not operate the detector in a combustible atmosphere since its sensor operates at high temperature.

Perform a refrigerant leak test on the system when the following conditions exist:

Tools Required

J 39400 Electronic Leak Detector

The J 39400 is a small unit which operates on a 12V DC.

The detector provides an audible signal. The signal increases in frequency as R-134a is detected.

Use the included instructions in order to ensure that the instrument is properly calibrated. Ensure that the detector is used in the proper setting for the type of refrigerant being tested.

Place the detector gas switch in the R-134a setting prior to use.

Inspect the refrigerant fittings and the connections for leaks. The following conditions may cause leaks:

When using the electronic leak detector, ensure that the following conditions exist:

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

1. Windshield washing solutions
2. Solvents and cleaners
3. Adhesives

A leak is indicated when the audible tone changes from a steady 1-2 clicks per second to a solid alarm. Frequently adjust the balance knob in order to maintain the 1-2 clicks per second rate.

Important: Always follow the refrigerant system around in a continuous path so that no areas of potential leaks are missed. Always test all of the following areas in order to ensure that the entire system is leak free, even when one leak is already found.

Use this procedure in order to test the following areas:

The sealing gap is the primary seal for the service ports. This cap contains a specially designed O-ring seal or gasket which provides a leak-free seal.

The following conditions will result in the loss of refrigerant charge:

Leaks in the A/C evaporator core may be difficult to detect. Use the following procedure in order to test the core:

1. Turn the blower fan on HIGH for 15 or more seconds.
2. Turn off the blower fan.
3. Wait 10 minutes.
4. Remove the blower mower resistor.
5. Insert the leak detector probe. Be sure to insert the leak detector as close to the A/C evaporator as possible.
6. Listen to the detector. If the detector sounds a solid alarm, a leak has been found.
7. Visually inspect the core face with a flashlight for evidence of refrigerant oil.

1. Blow shop air behind and in front of the A/C compressor armature/pulley for 15 seconds or more.
2. Wait 1-2 minutes.
3. Probe the area in front of the pulley.
4. Listen to the detector. If the detector sounds a solid alarm, a leak has been found.

Before disassembling any A/C compressor components, inspect for leaks. Replace the A/C compressor if a leak is found in any of the following areas:

Tools Required

The following diagnostic procedure should be used when an A/C refrigerant leak cannot be found when using a leak detector, J 39400-A.

1. Recover the refrigerant from the system and record refrigerant weight. Refer to Refrigerant Recovery and Recharging in this section.
2. Add J 41447 Fluorescent Tracer Dye or GM P/N 12346303, using J 41459 R-134a A/C Tracer Dye Injector .
3. Recharge the system. Refer to Refrigerant Recovery and Recharging in this section.

Important: R 134a florescent dye will remain in the system for the life of the vehicle as long as the vehicle's A/C system has not been flushed.

4. Check the system for leaks using a High Intensity Black Light.