Maximum Heater Output: Test And Action: Notes
Engine coolant is provided to the heater system through two heater hoses. With the engine idling at normal operating temperature, set the temperature control to maximum heat 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 from the floor outlets. Compare the test thermometer reading to the Heater Temperature Reference chart.
| Ambient Air Temperature | 16° C (60° F) |
21° C (70° F) |
26° C (80° F) |
32° C (90° F) |
|---|---|---|---|---|
| Minimum Air Temperature at Floor Outlet | 62° C (144° F) |
64° C (147° F) |
65° C (150° F) |
67° C (153° F) |
See ENGINE COOLING SYSTEM if the heater outlet air temperature is below the minimum specification. 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.