Heater Core: Testing and Inspection
Heater Core Leak TestHeater Core Leak Test Heater core leaks can be indicated by wet carpeting and coolant odor in the passenger compartment.
An inadequate seal between the heater core tubes can allow coolant to follow the tube to the heater core and appear as a leak. If a heater core leak is suspected, use the following procedures.
Inspection
1. Look for evidence of coolant leakage at the heater water hose-to-heater core attachments.
2. Check the system for loose heater hose clamps.
3. If a leak is found and the hose clamps are tight, check the heater core tubes for distortion or evidence of being bent out of shape. Severe distortion of the heater core water tubes could cause leakage at the heater water hose connection.
Pressure Test - Heater Core In-Vehicle
1. Drain the coolant from the cooling system.
2. Access the auxiliary air conditioning and heating system assembly, located behind the LH quarter trim panel.
3. Disconnect the heater water hose from the heater core tubes.
4. Install a short piece of heater water hose approximately 10cm (4 inches) in length on each heater core tube.
5. Prepare the heater core as follows:
a. Fill the heater core and heater water hoses with water.
b. Install Plug BT-7422-B in one hose end and Adapter BT-7422-A from Rotunda Radiator / Heater Core Pressure Tester 021-00012 or equivalent in the other hose end.
c. Secure the hoses, plug, and adapter with hose clamps.
6. Pressure test the heater core as follows:
a. Attach the Rotunda Radiator/Heater Core Pressure Tester 021-00012 or equivalent to Adapter BT-7422-A on the heater hose.
b. Close the bleed valve at the base of the gauge.
c. Pump 103 kPa (15 psi) of air pressure into the heater core.
7. Observe the pressure gauge for a minimum of three minutes. The pressure should not drop.
8. If the pressure does not drop, the heater core does not leak.
9. If the pressure drops, check the hose connections to the heater core tubes for leaks. If the hoses do not leak, remove the heater core from the vehicle and perform the Heater Core On-Bench Pressure Test.
Pressure Test - Heater Core On-Bench
1. Drain all coolant from the heater core.
2. Attach the heater water hoses with the plug and adapter to the heater core tubes as indicated in the Heater Core In-Vehicle Pressure Test.
3. Attach the Rotunda Radiator/Heater Core Pressure Tester 021-00012, or equivalent, to the adapter.
4. Pump 103 kPa (15 psi) of air pressure into the heater core.
5. Submerge the heater core in water.
6. If a leak is observed, service or replace the heater core.
Aux Evaporator Core Leak Test
On-Vehicle Leak Test
NOTE: Before disconnecting any A/C components, the system must first be discharged and the refrigerant recovered.
1. Disconnect the liquid line and suction accumulator/drier from the aux 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 aux 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).
2. Connect the appropriate test fittings from Test Adapter Set D88P- 19703-B or equivalent to the aux 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.
NOTE: The automatic shut-off valves on some gauge set hoses do not open when connected to the test fittings. Use hoses without shut-off valves if available. If hoses with shut-off 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 shut-off valve does not open because only the hose will be tested.
3. Open both gauge set valves and start the vacuum pump. Turn the aux heater blower motor on speed 1 and allow the vacuum pump to operate for a minimum of 1/2 hour after the gauge set low pressure gauge indicates 30 in-Hg. This 1/2 hour evacuation is necessary to remove any refrigerant from oil left in the aux 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 1/2 hour, close the gauge set valves and stop the vacuum pump. Observe the low pressure gauge: it should remain at the 30 in-Hg mark.
NOTE: Use only a quality vacuum pump. A vacuum pump, like an automobile, requires maintenance for optimum performance. The condition of the vacuum pump oil is critical to pump performance and durability. Dirty and / or moisture laden oil reduces the vacuum pumps ability to draw high vacuum levels which are required to extract refrigerant from the oil in the evaporator core. As a general rule, vacuum pump manufacturers recommend replacing the oil in the vacuum pump after every 10 hours of operation. Some manufacturers may recommend even more frequent oil change intervals.
4. If the low pressure gauge reading will not drop to 30 in-Hg when the gauge set 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 aux evaporator core.
5. If the low pressure gauge reading rises 10 or more inches of vacuum from the 30 in-Hg mark in ten minutes, a leak is indicated. If a very 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 30 minutes with the heater blower motor on speed 1 to remove any remaining refrigerant from the aux evaporator core. Then, recheck for loss of vacuum as outlined above. If a very small leak is suspected, allow the system to sit overnight with vacuum applied and check for vacuum loss the next day. Always remember that a leaking fitting, gauge set, or hose connection will appear as a leaking aux evaporator core.
6. 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.