Checking Refrigerant Leaks
PRELIMINARY CHECKPerform a visual inspection of all refrigeration parts, fittings, hoses, and components for signs of A/C lubricant leakage, damage and corrosion.
Precautions For Handling Leak Detector:
PRECAUTIONS FOR HANDLING LEAK DETECTOR
When performing a refrigerant leak check, use a J39400 A/C leak detector or equivalent. Ensure that the instrument is calibrated and set properly per the operating instructions.
The leak detector is a delicate device. In order to use the leak detector properly, read the operating instructions and perform any specified maintenance.
Other gases in the work area or substances on the A/C components, for example, anti-freeze, windshield washer fluid, solvents and cleaners, may falsely trigger the leak detector. Make sure the surfaces to be checked are clean. Do not allow the sensor tip of the detector to come into contact with any substance. This can also cause false readings and may damage the detector.
1. Position probe approximately 5 mm (3/16 in) away from point to be checked.
2. When testing, circle each fitting completely with probe.
3. Move probe along component approximately 25 to 50 mm (1 to 2 in)/sec.
Checking Procedure
To prevent inaccurate or false readings, make sure there is no refrigerant vapor or tobacco smoke in the vicinity of the vehicle. Perform the leak test in calm area (low air/wind movement so that the leaking refrigerant is not dispersed.
1. Turn engine OFF.
2. Connect a suitable A/C manifold gauge set to the A/C service ports.
3. Check if the A/C refrigerant pressure is at least 345 kPa (3.52 kg/Sq cm, 50 psi) above 16 °C (61 °F). If less than specification, evacuate and recharge the system with the specified amount of refrigerant.
NOTE: At temperatures below 16 °C (61 °F), leaks may not be detected since the system may not reach 345 kPa (3.52 kg/Sq cm, 50 psi).
4. Conduct the leak test from the high side to the low side at points athrough k. Perform a leak check for the following areas carefully. Clean the component to be checked and move the leak detector probe completely around the connection/component.
- Compressor
Check the fitting of high and low pressure hoses, relief valve and shaft seal.
- Liquid tank
Check the pressure switch, tube fitting, weld seams and the fusible plug mounts.
- Service valves
Check all around the service valves. Ensure service valve caps are secured on the service valves (to prevent leaks).
NOTE: After removing A/C manifold gauge set from service valves, wipe any residue from valves to prevent any false readings by leak detector.
- Cooling unit (Evaporator)
Turn blower fan on "High" for at least 15 seconds to dissipate any refrigerant trace in the cooling unit. Insert the leak detector probe into the drain hose immediately after stopping the engine. (Keep the probe inserted for at least 10 seconds.)
5. If a leak detector detects a leak, verify at least once by blowing compressed air into area of suspected leak, then repeat check.
6. Do not stop when one leak is found. Continue to check for additional leaks at all system components.
7. Start engine.
8. Set the heater A/C control as follows:
a. A/C switch ON
b. Face mode
c. Recirculation switch ON
d. Max cold temperature
e. Fan speed high
9. Run engine at 1,500 rpm for at least 2 minutes.
10. Turn engine oft and perform leak check again following steps 4 through 6 above.
Refrigerant leaks should be checked immediately after stopping the engine. Begin with the leak detector on the high pressure line. The pressure in the high pressure line will gradually drop after refrigerant circulation stops and pressure in the low pressure line will gradually rise, as shown in the graph. Leaks are more easily detected when pressure is high.
11. Discharge A/C system using approved refrigerant recovery equipment. Repair the leaking fitting or component as necessary.
12. Evacuate and recharge A/C system and perform the leak test to confirm no refrigerant leaks.
13. Conduct A/C performance test to ensure system works properly.