Before performing the following tests, refer to Group 7 - Cooling for the procedures to check the engine coolant level and flow, engine coolant reserve/recovery system operation, accessory drive belt condition and tension, radiator air flow and the fan drive operation.
WARNING: Do not remove radiator cap when engine is hot, personal injury can result.
If vehicle has been run recently, wait 15 minutes before removing the radiator cap. Place a rag over the cap and turn it to the first safety stop. Allow pressure to escape through the overflow tube. When the system pressure stabilizes, remove the cap completely.
Engine coolant is delivered to and from 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 front floor outlets. Compare the test thermometer reading to the Heater Temperature Reference chart.
|
Ambient Temperature |
Minimum Floor Outlet Temperature |
||
|
Celsius |
Fahrenheit |
Celsius |
Fahrenheit |
|
16 degrees |
60 degrees |
54 degrees |
130 degrees |
|
21 degrees |
70 degrees |
56 degrees |
132 degrees |
|
27 degrees |
80 degrees |
57 degrees |
134 degrees |
|
32 degrees |
90 degrees |
58 degrees |
136 degrees |
If the heater outlet air temperature is below the minimum specification, refer to Group 7 - Cooling. 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 Group 7 - Cooling for more information.
Possible locations or causes of obstructed coolant flow are as follows:
If proper coolant flow through the cooling system is verified, and heater outlet air temperature is low, a mechanical problem may exist.
Possible causes of insufficient heat due to mechanical problems are as follows:
If the heater outlet air temperature cannot be adjusted with the temperature control on the A/C-heater control, the following could require service: