Test B: Insufficient, Erratic Or No Heat

PINPOINT TEST B: INSUFFICIENT, ERRATIC OR NO HEAT

Normal Operation
Under normal operation, warm coolant flows from the engine through the heater core and back to the engine.

This pinpoint test is intended to diagnose the following:
- Plugged heater core
- Coolant level
- Temperature blend door

B1:

B2-B3:

B4: