Functional Check (Heater)

Before beginning the functional test of the heater system, the engine must idle with the coolant hot and the thermostat open. The coolant temperature must be about 90 °C (194 °F). During the function test, evaluate the operating efforts of the mode control knob and the temperature control knob. Even if a problem is found during any intermediate step of the function test, complete the test before the repair is started.

Function Test: