Leak Testing
Leak Testing
Caution: Avoid breathing the A/C Refrigerant 134a (R-134a) and the lubricant vapor or the mist. Exposure may irritate the eyes, nose, and throat. Work in a well ventilated area. In order to remove R-134a from the A/C system, use service equipment that is certified to meet the requirements of SAE J 2210 (R-134a recycling equipment). If an accidental system discharge occurs, ventilate the work area before continuing service. Additional health and safety information may be obtained from the refrigerant and lubricant manufacturers.
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 when the following conditions exist:
* A leak is suspected.
* A service operation disturbs the components, lines or connections.
Electronic Leak Detector
Tools Required
J 39400 Electronic Leak Detector
The J 39400 is a small unit which operates on 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:
* Improper torque
* Damaged O-ring seals
* Lack of lubricant on the O-ring seals
* Dirt or debris across the O-ring seals
* Small pieces of lint from cotton gloves or shop cloths
When using the electronic leak detector, ensure that the following conditions exist:
* Each joint is completely circled.
* The scan rate is 25-51 mm (1.2 in) per second.
* The tip of the probe is no more than 6 mm (0.25 in) away from the surface. Place the tip of the probe as close to the surface as possible.
* The air intake is not blocked.
Important: Halogen leak detectors are sensitive to the following compounds:
* Windshield washing solutions
* Solvents and cleaners
* Adhesives
In order to prevent a false warning, ensure that all of the surfaces are clean.
Ensure that surfaces are dry. The ingestion of liquids will damage the detector.
A leak is indicated when the audible tone changes from a steady 1-2 clicks per second to a solid alarm. Adjust the balance knob frequently 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 evaporator inlet and outlet
* The accumulator inlet and outlet
* The condenser inlet and outlet
* All brazed and welding areas
* All areas that exhibit signs of damage
* The hose couplings
* The compressor rear head
* The housing joints
Service Ports/Access Valves
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:
* A loose cap
* A missing cap
* The use of a wrong cap
Evaporator Core
Leaks in the 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 for 10 minutes.
4. Remove the blower motor resistor. Refer to Blower Motor Resistor Replacement Service and Repair in Heating and Ventilation (Non-A/C).
5. Insert the leak detector probe. Be sure to insert the leak detector as close to the 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.
Compressor Block Fitting and Shaft Seal
1. Blow shop air behind and in front of the compressor clutch/pulley for 15 or more seconds.
2. Wait for 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.