Leak Detection
Checking for A/C LeaksAvoid breathing A/C refrigerant and lubricant vapor or mist. If accidental system discharge occurs, ventilate the work area before resuming service.
WARNING: GOOD VENTILATION IS NECESSARY IN THE AREA WHERE A/C LEAK TESTING IS TO BE DONE. IF THE SURROUNDING AIR IS CONTAMINATED WITH REFRIGERANT GAS, THE LEAK DETECTOR WILL INDICATE THIS GAS ALL THE TIME. ODORS FROM OTHER CHEMICALS.SUCH AS ANTIFREEZE, DIESEL FUEL, DISC BRAKE CLEANER OR OTHER CLEANING SOLVENTS CAN CAUSE THE SAME CONCERN. A FAN, EVEN IN A WELL-VENTILATED AREA, IS VERY HELPFUL IN REMOVING SMALL TRACES OF AIRBORNE CONTAMINATION THAT MIGHT AFFECT THE LEAK DETECTOR.
Attach the Rotunda R-134a Service Center 176-00001 or equivalent to the system. Leave both manifold gauge valves at the maximum open position. Both gauges should show approximately 413-551 kPa (60-80 psi) at 24°C (75°F) with engine not running.
Leak Detector, Electronic
Check all system connections, the compressor head gasket and shaft seal for leaks, using a good leak detector. Use Rotunda R-134a Automatic Calibration Halogen Leak Detector 161-ROOlO or equivalent. Pass the leak detector along the underside of all points being checked. Refrigerant is heavier than air and will show most readily in those locations.
Operate leak detector according to manufacturer's directions.
A/C Evaporator Core and/or A/C Condenser Core
When performing leak tests of the A/C evaporator core with an electronic leak detector, test only at the evaporator core drain tube and the evaporator core refrigerant line connections. Do not attempt to leak test at the instrument panel A/C registers or inside the passenger compartment. Airflow from the blower motor and/or chemical odors inside the vehicle may cause false readings. This is especially important after the vehicle has sat in the sun and the interior temperature has risen above the ambient level.
If an A/C evaporator core leak is suspected, the leak test procedure should be performed before replacing the A/C evaporator core. Use of this leak test procedure will help to prevent unnecessary replacement of non-leaking A/C evaporator cores. If a leak is indicated at a refrigerant line connection to the A/C evaporator core, remove the refrigerant from the system and disassemble the fitting. Clean the fitting components and inspect for damage. Service as necessary.
NOTE: Use the previous procedure to also test the A/C condenser core.
On-Vehicle Leak Test
Disconnect the liquid line and suction accumulator / drier from the evaporator core tubes. DO NOT leak test an A/C evaporator core with the suction accumulator / drier attached to the A / C evaporator core. If the evaporator core tube fittings are the female spring lock design, check the inside of each fitting if possible for scratches and/or corrosion. If scratches or corrosion are found, the leak test results may not be accurate if a leak is indicated because of possible leaks at the fitting(s).
Connect the appropriate test fittings from Test Adapter Set D93L-19703-B or equivalent to the evaporator tube connections. Then, connect the gauge set RED and BLUE hoses to the test fittings. Connect the YELLOW gauge set hose to a known quality vacuum pump.
Before leak testing the A/C evaporator core, attach the high-side and low-side manifold gauge set hoses together and apply vacuum to verify the manifold gauge set and the hoses do not leak.
NOTE: The automatic shutoff valves on some gauge set hoses do not open when connected to the test fittings. Use hoses without shutoff valves if available. If hoses with shutoff valves are used, check to be sure the valve opens when attached to the test fittings before installing the fittings and proceeding with the leak test. The test is not valid if the shutoff valve does not open because only the hose will be tested.
Open both gauge set valves and start the vacuum pump. Turn the blower motor on low and allow the vacuum pump to operate for a minimum of 45 minutes after the gauge set low pressure gauge indicates 30 in-Hg. This evacuation is necessary to remove any refrigerant from oil left in the A/C evaporator core. If the refrigerant is not completely removed from the oil, gassing will occur and degrade the vacuum and appear as a refrigerant leak. After evacuating for 45 minutes, close the gauge set valves and stop the vacuum pump. Observe the low pressure gauge. It should remain at the 30 mark.
NOTE: Use only a known quality vacuum pump. Make sure pump is maintained according to manufacturer's directions.
If the low-pressure gauge reading will not drop to 30 in-Hg when the valves are open and the vacuum pump is operating, close the gauge set valves and observe the low pressure gauge. If the pressure rises rapidly to zero, a large leak is indicated. Recheck the test fitting connections and gauge set connections before replacing the A/C evaporator core.
If the low pressure gauge reading rises 10 or more inches of vacuum from the 30 inch position in ten minutes, a leak is indicated. If a small leak is suspected, wait 30 minutes and observe the vacuum gauge. If a small amount of vacuum is lost, operate the vacuum pump with the gauge valves open for an additional 45 minutes with the system blower motor on low to remove any remaining refrigerant from the oil in the A/C evaporator core. Then, recheck for loss of vacuum. If a very small leak is suspected, allow the system to sit overnight with vacuum applied and check for vacuum loss. Always remember that a leaking fitting, gauge set or hose connection will appear as a leaking A/C evaporator core.
If a vehicle passes the vacuum leak test and is returned within 60 days for loss of cooling due to no refrigerant charge, look elsewhere in the system for refrigerant leaks such as the compressor shaft seal or refrigerant line connections.