Caution: Avoid breathing A/C Refrigerant-134a and lubricant vapor and 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 system discharge occurs, ventilate work area before resuming service. Additional health and safety information may be obtained from refrigerant and lubricant manufacturers.

Perform a refrigerant leak test on the system whenever you suspect a leak. Perform a refrigerant leak test on the system following a service operation that disturbs the components, the lines, or the connections. Many methods and special tools are available for this purpose. However, no matter which tool is used, care and diligence are the biggest keys to success.

Tools Required

J 39400 Electronic Leak Detector

This type of leak detector is the most useful tool in locating refrigerant leaks. The J 39400 is a small unit that operates on 12V DC. The J 39400 provides an audible signal that increases in frequency as R-134a is detected. Make sure the instrument is properly calibrated in accordance with the included instructions. Use the detector in the proper setting for the type of refrigerant being tested. Place the detector GAS switch in the R-134a setting prior to use.

The most common leaks are found at the refrigerant fittings or connections. The causes of common leaks may be the following conditions:

Even the smallest piece of lint from cotton gloves or shop cloths can create a leak path across an O-ring seal.

Important: The halogen leak detectors are sensitive to windshield washing solutions, many solvents and cleaners, and some adhesives used in the vehicle. Prevent a false warning by making sure the surfaces are clean. Also, the surfaces should be dry, because the ingestion of liquids damages the detector.

The successful use of this and any other electronic leak detector depends greatly upon the scan rate. The successful use of the detector depends upon the carefully following the manufacturer's instructions regarding calibration, operation and maintenance.

Circle each joint completely. Move the probe at 25-51 mm (1-2 in) per second. Move the tip of the probe as close to the surface as possible, but no more than 6 mm (0.25 in) away. Do not block the air intake. The audible tone going from a steady 1-2 clicks per second to an a solid alarm indicates a leak. Frequently adjust the balance knob in order to maintain the rate of 1-2 clicks per second.

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.

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

Use this procedure in order to test the following components and locations in the system:

Service Ports/Access Valves

The primary seal for the service ports is the sealing cap. This cap contains a specially designed O-ring seal or gasket that provides a leak-free seal. A loose or missing cap, or using the wrong cap, results in the loss of the refrigerant charge.

Evaporator Core

Finding leaks in the evaporator core is very difficult. In order to leak test the core, complete the following steps:

1. Turn the blower fan to the HI position for 15 seconds or longer.

Then, turn the blower fan to the OFF position.

2. Wait 10 minutes.
3. Remove the blower motor resistor. Refer to Blower Motor Resistor Replacement .
4. Insert the probe of the leak detector as close to the evaporator as possible.

A solid alarm indicates the discovery of a leak.

5. If possible, visually inspect the core face for evidence of refrigerant oil. Use a flashlight.

Compressor Block Fitting and Shaft Seal

Complete the following steps:

1. Blow shop air behind and in front of the compressor clutch/puller for at least 15 seconds.
2. Wait 1-2 minutes.
3. Probe the area in front of the pulley.

A solid alarm indicates the discovery of a leak.