Multi-Function Thermal Sensor / Switch: Description and Operation

The PTC is built into the control unit. It has a variable resistance which changes according to the set temperature. This resistance is connected to the temperature knob.

PTC
After disconnecting PTC harness connector, measure resistance between terminals 1 and 2 at PTC harness side.











PBR
Measure resistance between terminals 1 and 2 at vehicle harness side.

IGNITION SWITCH: ON
Ensure tester pointer deflects smoothly when PTC is moved from 20 °C (65 °F) to 30 °C (85 °F) and vice versa.