Heater Core: Testing and Inspection
HEATER COREWARNING: CARBON MONOXIDE IS COLORLESS, ODORLESS AND DANGEROUS. IF IT IS NECESSARY TO OPERATE THE ENGINE WITH THE VEHICLE IN A CLOSED AREA SUCH AS A GARAGE, ALWAYS USE AN EXHAUST COLLECTOR TO VENT THE EXHAUST GASES OUTSIDE THE CLOSED AREA.
1. Perform a system inspection by checking the heater system thoroughly as follows: Inspect for evidence of coolant leakage at the heater water hose to heater core attachments. A coolant leak in the heater water hose could follow the heater core tube to the heater core and appear as a leak in the heater core.
NOTE: Testing of returned heater cores revealed that a large percentage of heater cores were good and should not have been replaced. If a heater core leak is suspected, the heater core should be tested as outlined in the Plugged Heater Core procedures before pressure testing the heater core.
2. Check the integrity of the heater water hose clamps.
3. Spring-type clamps are installed as original equipment. Use of non-specification clamps can cause leakage at the heater water hose connection and damage the heater core.
PLUGGED HEATER CORE
WARNING: THE HEATER CORE INLET HOSE WILL BECOME TOO HOT TO HANDLE IF THE SYSTEM IS WORKING CORRECTLY.
Check to see that the engine coolant is at the proper level. Start the engine and turn on the heater. When the engine coolant reaches operating temperature, feel the heater core outlet hose to see if it is hot. If it is not hot, the heater core may have an air pocket, or may be plugged, or the thermostat is not working properly.
PRESSURE TEST
Use Radiator Pressure Tester O14-R1069 or equivalent to perform the pressure test.
NOTE: Due to space limitations, a bench test may be necessary for pressure testing.
1. Drain the coolant from the cooling system.
2. Disconnect the heater water hoses from the heater core.
3. Install a short piece of heater water hose, approximately 101 mm (4 inches) long on each heater core tube.
4. Fill the heater core and heater water hoses with water and install Plug BT-7422-B and adapter BT-7422-A from Radiator Pressure Tester 014-R1069 or equivalent in the heater water hose ends. Secure the heater water hoses, plug, and adapter with hose clamps and tighten.
5. Attach the pump and gauge assembly from Radiator Pressure Tester 014-R1069 or equivalent to the adapter.
6. Close the bleed valve at the base of the gauge and pump 241 kPa (35 psi) of air pressure into the heater core.
7. Observe the pressure gauge for a minimum of three minutes.
8. If the pressure drops, check the heater water hose connections to the core tubes for leaks. If the heater water hoses do not leak, test the heater core as follows:
1. Drain all coolant from the heater core.
2. Remove the heater core from the A/C evaporator housing.
3. Connect the 101 mm (4 inch) test heater water hoses with plug and adapter to the core tubes. Then connect Radiator Pressure Tester 014-R1069 or equivalent to the adapter.
4. Apply 241 kPa (35 psi) of air pressure to the heater core. Submerge the heater core in water.
5. If a leak is observed, service or replace the heater core (as necessary).