Maximum Heater Output

Temperature Reference Chart:

Engine coolant is provided to the heater system by two heater hoses. With engine idling at normal running temperature, set the control to MAXIMUM HEAT, FLOOR and HIGH blower settings. Using a test thermometer, check the air temperature coming from the floor outlets, refer to Temperature Reference Chart.

If the Floor Outlet Air Temperature is still low, additional diagnoses can be found under Cooling Systems:
-Cooling System/
-Testing and Inspection/
-Procedures/
-Diagnosis and Symptoms/
-Heater Core Problems
Heater Core Problems

Both heater hoses should be HOT to the touch. The coolant return hose should be slightly cooler than the supply hose. If coolant return hose is much cooler than the supply hose, locate and repair engine coolant flow obstruction in heater system.

Possible locations or cause of obstructed coolant flow:
- Pinched or kinked heater hoses.
- Improper heater hose routing.
- Plugged heater hoses or supply and return ports at cooling system connections.
- Plugged heater core.

If proper coolant flow through heater system is verified and outlet air temperature is still low, a mechanical problem may exist. Possible location or cause of insufficient heat:
- Obstructed cowl air intake.
- Obstructed heater system outlets.
- Blend-air door not functioning properly.