Heater Core Case: Testing and Inspection

HEATER UNIT

INSPECTION

1. CHECK HEATER RADIATOR FINS FOR BLOCKAGE
If the fins are clogged, clean them with compressed air.

2. CHECK FITTING FOR CRACKS OR SCRATCHES
If necessary repair or replace.




3. PTC heater models only:
INSPECT PTC HEATER CONTINUITY
Using an ohmmeter, check continuity exists between each terminal of connector and earth wire.
If no continuity exists, replace the heater radiator.




4. PTC heater models only:
INSPECT WATER TEMPERATURE SENSOR
Measure resistance between terminals at each temperature.

Standard resistance:
25 °C (77 °F): 5.0 ± 0.2 kohm
40 °C (104 °F): 2.7 ± 0.15 kohm
100 °C (212 °F): 0.3 ± 0.04 kohm

If resistance is not as specified, replace the sensor.




5. Two way flow heater models only:
INSPECT MICRO SWITCH CONTINUITY
Check the continuity exists between terminals while switch is pressed.
If no continuity exists, replace the switch.