Functional Test - Without A/C

Heater System Function Test:

Vacuum Schematic:

FUNCTIONAL TEST
Before beginning the functional test of the heater system, the engine should be idling with the coolant hot and thermostat open. Coolant temperature should be about 90°C (194°F). During the functional test, the operating efforts of the mode lever or control knob and the temperature lever or control knob should be evaluated. Even if a problem is found during any intermediate step of the functional test, the test should be completed before repair is started (see accompanying figures).