Heater Performance Test
Engine coolant is delivered to the heater core through two heater hoses. With the engine idling at normal operating temperature, set the temperature control to the full hot position, the mode control to the floor position, and the blower motor control to the highest speed position. Using a test thermometer, check the temperature of the air being discharged at the HVAC housing floor outlets. Compare the test thermometer reading to the Heater Temperature Reference chart.
| Ambient Temperature | Minimum Floor Outlet Temperature | ||
|---|---|---|---|
| Celsius | Fahrenheit | Celsius | Fahrenheit |
| 15.5° | 60° | 62.2° | 144° |
| 21.1° | 70° | 63.8° | 147° |
| 26.6° | 80° | 65.5° | 150° |
| 32.2° | 90° | 67.2° | 153° |
If the heater outlet air temperature is below the minimum specification, refer to COOLING - EXCEPT COUPE . Both of the heater hoses should be hot to the touch. The coolant return heater hose should be slightly cooler than the coolant supply heater hose. If the return hose is much cooler than the supply hose, locate and repair the engine coolant flow obstruction in the cooling system. Refer to COOLING - EXCEPT COUPE for more information.
OBSTRUCTED COOLANT FLOW
- Faulty water pump.
- Faulty thermostat.
- Pinched or kinked heater hoses.
- Improper heater hose routing.
- Plugged heater hoses or supply and return ports at the cooling system connections.
- A plugged heater core.
- Air locked heater core or air in cooling system.
If proper coolant flow through the cooling system is verified, and heater outlet air temperature is still low, a mechanical problem may exist.
MECHANICAL PROBLEMS
Possible locations or causes of insufficient heat:
- An obstructed cowl air intake.
- Obstructed heater system outlets.
- A faulty, obstructed or improperly installed blend-air door or actuator.
- A faulty blower system.
- A faulty A/C-heater control.