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Evaporator/Condenser, On-Vehicle Leak Test

WARNING: This page is about a different car, the 2002 Mercury Villager. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Do Not leak test an evaporator core with accumulator-drier attached to core tubes.
NOTE: The automatic shut-off valves on some gauge set hoses do not open when connected to test fittings. If available, use hoses without shut-off valves. If hoses with shut-off valves are used, make sure valve opens when attached to test fittings or install an adapter which will activate valve. Test is not valid if shut-off valve does not open.
  1. Discharge A/C system, using approved recovery/recycling equipment. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING.
  2. Disconnect evaporator core or condenser from A/C system.
  3. Clean spring lock couplings. See CLEANING SPRING LOCK COUPLINGS  under ON VEHICLE SERVICE. Connect appropriate test fittings to evaporator or condenser tube connections.
  4. Connect red and blue hoses from R-134a Manifold Gauge Set to test fittings on evaporator core or condenser. Connect yellow hose to a known good vacuum pump.
  5. Open both gauge set valves and start vacuum pump. Allow vacuum pump to operate for a minimum of 45 minutes after gauge set low pressure gauge indicates 30 in. Hg (101 kPa). A 45 minute evacuation is necessary to remove any refrigerant from oil left in evaporator core or condenser. If refrigerant is not completely removed from oil, outgassing will degrade vacuum and appear as a refrigerant leak.
  6. If low pressure gauge reading will not drop to 30 in. Hg (101 kPa) when valves on gauge and manifold set are open and vacuum pump is operating, close gauge set valves and observe low pressure gauge. If pressure rises rapidly to zero, a large leak is indicated. Recheck test fitting connections and gauge set connections before replacing evaporator core or condenser.
  7. After evacuating for 45 minutes, close gauge set valves and stop vacuum pump. Observe low pressure gauge, it should remain at 30 in. Hg (101 kPa) mark.
  8. If low pressure gauge reading rises 10 or more in. Hg (34 or more kPa) of vacuum from 30 in. Hg (101 kPa) position in 10 minutes, a leak is indicated.
  9. If a very small leak is suspected, wait 30 minutes and observe vacuum gauge.
  10. If a small amount of vacuum is lost, operate vacuum pump with gauge valves open for an additional 30 minutes to remove any remaining refrigerant from oil in evaporator core or condenser. Then recheck for loss of vacuum.
  11. If a very small leak is suspected, allow system to set overnight with vacuum applied and check for vacuum loss.
  12. If evaporator core or condenser does leak, as verified by above procedure, install a new evaporator core or condenser.
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