Step
| Action
| Yes
| No
|
DEFINITION: Heating system performance.
|
1
| Were you sent here from Symptoms or another diagnostic table?
| Go to
Step 2
| Go to
Symptoms - HVAC Systems - Manual
|
2
|
- Start the engine.
- Allow the engine to idle.
Does the engine reach a normal operating temperature?
| Go to
Step 3
| Go to
Step 9
|
3
|
- Allow the engine to idle.
- Select the FLOOR mode.
- Select the minimum blower speed.
- Select the warmest temperature setting.
- Feel the temperature of the inlet and outlet heater hoses at the heater core.
Does the inlet heater hose feel warmer than the outlet heater hose?
| Go to
Step 7
| Go to
Step 4
|
4
|
- Install a thermometer into the center instrument panel (l/P) PANEL air outlet.
- Secure a thermometer to the heater core outlet hose.
- Select the PANEL mode.
- Select the maximum blower speed.
- Select the warmest temperature setting.
- Record the temperature at the following locations:
• | The center I/P PANEL air outlet |
• | The heater core outlet hose |
- Compare the recorded temperatures.
Are the two temperature readings about equal?
| Go to
Step 5
| Go to
Step 6
|
5
|
- Inspect and repair the following areas of the vehicle for cold air leaks:
- Perform the necessary repairs.
Are the repairs complete?
| Go to
Step 10
| --
|
6
|
- Inspect the temperature door operation. Refer to
Diagnostic System Check - Vehicle
.
- Perform any necessary repairs.
Are the repairs complete?
| Go to
Step 10
| --
|
7
|
- Turn OFF the engine.
- Backflush the heater core.
- Start the engine.
- Select the FLOOR mode.
- Select the minimum blower speed.
- Select the warmest temperature setting.
- Feel the temperature of the inlet and outlet heater hoses at the heater core.
Does the inlet heater hose feel warmer than the outlet heater hose?
| Go to
Step 8
| Go to
Step 10
|
8
| Replace the heater core. Refer to
Heater Core Replacement
.
Is the repair complete?
| Go to
Step 10
| --
|
9
| Repair the low engine temperature concern. Refer to
Engine Fails To Reach Normal Operating Temperature
.
Is the repair complete?
| Go to
Step 10
| --
|
10
| Operate the system in order to verify the repair.
Did you find and correct the condition?
| System OK
| Go to
Step 2
|