Refrigerant: Testing and Inspection
Checking Refrigerant LeaksPRELIMINARY CHECK
- Perform a visual inspection of all refrigeration parts, fittings, hoses and components for signs of A/C lubricant leakage, damage and corrosion. A/C lubricant leakage may indicate an area of refrigerant leakage.
Allow extra inspection time in these areas when using either an electronic refrigerant leak detector or fluorescent dye leak detector.
- If dye is observed, confirm the leak with an approved electronic refrigerant leak detector. It is possible a prior leak was repaired and not properly cleaned.
- When searching for leaks, do not stop when one leak is found but continue to check for additional leaks at all system components and connections.
- When searching for refrigerant leaks using an electronic leak detector, move the probe along the suspected leak area at 25 - 50 mm (1 - 2 in) per second and no further than 1/4 inch from the component.
NOTE: Moving the electronic leak detector probe slower and closer to the suspected leak area will improve the chances of finding a leak.
Electronic Refrigerant Leak Detector
PRECAUTIONS FOR HANDLING LEAK DETECTOR
When performing a refrigerant leak check, use a J-41995 electronic refrigerant 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 lubricants, may falsely trigger the leak detector. Make sure the surfaces to be checked are clean. Clean with a dry cloth or blow off with shop air.
- Do not allow the sensor tip of the detector to 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, shop chemicals, or cigarette 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, recover/evacuate and recharge the system with the specified amount of refrigerant. Refer to "HFC-134a (R-134a) Service Procedure".
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 (compressor discharge a to evaporator inlet g) to the low side (evaporator drain hose g to shaft seal l). Refer to "Checking Refrigerant Leaks". 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 mount.
- 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 seconds to dissipate any refrigerant trace in the cooling unit. Wait a minimum of 10 minutes accumulation time (refer to the manufacturer's recommended procedure for actual wait time) before inserting the leak detector probe into the drain hose.
Keep the probe inserted for at least ten seconds. Use caution not to contaminate the probe tip with water or dirt that may be in the drain hose.
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 steps 7 - 10.
7. Start engine.
8. Set the heater A/C control as follows:
1. A/C switch ON.
2. Face mode
3. Recirculation switch ON
4. Max cold temperature
5. Fan speed high
9. Run engine at 1,500 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 on 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 are more easily detected when pressure is high.
11. Before connecting the recovery/recycling recharging equipment to the vehicle, check recovery/recycling recharging equipment gauges. No refrigerant pressure should be displayed. If pressure is displayed, recover refrigerant from equipment lines and then check refrigerant purity.
12. Confirm refrigerant purity in supply tank using recovery/recycling recharging equipment and refrigerant identifier. Refer to "Contaminated Refrigerant".
13. Confirm refrigerant purity in vehicle A/C system using recovery/recycling recharging equipment and refrigerant identifier. Refer to "Contaminated Refrigerant".
14. Discharge A/C system using approved recovery/recycling equipment. Refer to "Discharging Refrigerant". Repair the leaking fitting or component as necessary.
15. Evacuate and recharge A/C system. Refer to "Evacuating System and Charging Refrigerant". Perform the leak test to confirm no refrigerant leaks.
16. Conduct A/C performance test to ensure system works properly.
Fluorescent Dye Leak Detector
PRECAUTIONS FOR FLUORESCENT DYE LEAK DETECTION
- The fluorescent dye leak detector is not a replacement for an electronic refrigerant leak detector. The fluorescent dye leak detector should be used in conjunction with an electronic refrigerant leak detector (J-41995) to pinpoint refrigerant leaks.
- For your safety and your customer's satisfaction, read and follow all manufacturer's operating instructions and precautions prior to performing the work.
- Refer to "Precautions for Leak Detection Dye".
CHECKING SYSTEM FOR LEAKS USING THE FLUORESCENT LEAK DETECTOR
1. Check A/C system for leaks using the UV lamp and safety glasses (J-42220) in a low sunlight area (area without windows preferable). Illuminate all components, fittings and lines. The dye will appear as a bright green/yellow area at the point of leakage. Fluorescent dye observed at the evaporator drain opening indicates an evaporator core assembly (tubes, core or expansion valve) leak.
2. If the suspected area is difficult to see, use an adjustable mirror or wipe the area with a clean shop rag or cloth, then check the cloth with the UV lamp for dye residue.
3. Confirm any suspected leaks with an approved electronic refrigerant leak detector.
4. After the leak is repaired, remove any residual dye using dye cleaner (J-43872) to prevent future misdiagnosis.
5. Perform a system performance check and verify the leak repair with an approved electronic refrigerant leak detector.
DYE INJECTION
(This procedure is only necessary when re-charging the system or when the compressor has seized and was replaced.)
Refer to "Precautions for Leak Detection Dye".
1. Check A/C system static (at rest) pressure. Pressure must be at least 345 kPa (3.52 kg/sq.cm, 50 psi).
2. Pour one bottle (1/4 ounce / 7.4 cc) of the A/C refrigerant dye into the injector tool (J-41459).
3. Connect the injector tool to the A/C LOW PRESSURE side service fitting.
4. Start engine and switch A/C ON.
5. With the A/C operating (compressor running), inject one bottle (1/4 ounce / 7.4 cc) of fluorescent dye through the low-pressure service valve using dye injector tool J-41459 (refer to the manufacturer's operating instructions).
6. With the engine still running, disconnect the injector tool from the service fitting.
CAUTION: Be careful not to allow dye to spray or drip when disconnecting the injector from the system.
NOTE: If repairing the A/C system or replacing a component, pour the dye directly into the open system connection and proceed with the service procedures.
7. Operate the A/C system for a minimum of 20 minutes to mix the dye with the system oil. Depending on the leak size, operating conditions and location of the leak, it may take from minutes to days for the dye to penetrate a leak and become visible.