Checking For 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.
Take note of the areas with A/C lubricant leakage to allow extra time in these areas with an electronic 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.
Other gases in the work area or substances on the A/C components, for example, anti-freeze, windshield washer fluid, solvents and lubricants, may falsely trigger the leak detector. Make sure the surfaces to be checked are clean. Clean with a dry cloth or blow oft with shop air. Do not allow the sensor tip of the detector to contact 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, shop chemicals or smoke in the vicinity of the vehicle. Perform the leak test in a 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, recovery/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 (shaft seal (m) and compressor discharge (a) to evaporator inlet (g) to the low side (evaporator drain hose (h) to compressor suction (i).
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)
With engine "off", turn blower fan on "High" for at least 15 secondsto dissipate any refrigerant trace in the cooling unit. Wait a minimum of ten minutes before inserting the leak detector probe into the drain hose. (keep the probe inserted for at least ten 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 as outlined above.
6. Do not stop when one leak is found. Continue to check for additional leaks at all system components. If no leaks are found, perform step 7-10.
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 1500 rpm for at least 2 minutes.
10. Turn engine off 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 at the compressor. The pressure in the high pressure side will gradually drop after refrigerant circulation stops and pressure on the low pressure side will gradually rise, as shown in the graph. Some leaks may be 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.