Insufficient Heat or Defrosting - Without A/C

Heater Performance Diagnosis:

INSUFFICIENT HEAT OR DEFROSTING
Check coolant level. Check the duct work for proper installation. Check blower operation. Inspect the temperature lever and the cable for proper installation and operation. Check the water control valve (if used) as follows:

1. Move the mode lever to "MAX" and the temperature lever to the right.
2. Start the engine and allow it to reach operating temperature.
3. Feel the hose from the water valve to the heater core. The hose should not be hot, indicating that vacuum is applied to the water control valve and the water supply to the heater core is turned off. When the mode lever is in any other position, water should flow to the heater core. If water does flow when in "MAX," or does not flow when in any other position, check the water control valve and the vacuum supply hose.
4. Vacuum should be applied to the water valve, stopping water flow to the heater core, when the temperature lever is moved to the maximum cold position and the mode lever is in any A/C position.