The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | Yes | No | ||||||||||||
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Schematic Reference: HVAC Schematics . DEFINITION: The temperature cannot be adjusted or the heating is insufficient. | ||||||||||||||||
1 | Did you review the HVAC operation and perform the necessary inspections? | -- | Go to Step 2 | |||||||||||||
2 |
Does the blower operate in any of the speed positions? | -- | Go to Step 3 | Go to Blower Motor Inoperative | ||||||||||||
3 | Does the blower actuator operate correctly for each speed position? | -- | Go to Step 4 | Go to Blower Motor Malfunction | ||||||||||||
4 | Is the HVAC control module inoperative? | -- | Go to Step 17 | Go to Step 5 | ||||||||||||
5 | Inspect the cooling system for the following:
Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 6 | ||||||||||||
6 |
Does the A/C compressor operate? | -- | Go to Step 7 | |||||||||||||
7 |
Does the air temperature door actuator drive shaft rotate at all? | -- | Go to Step 8 | Go to Step 9 | ||||||||||||
8 | Inspect the air temperature door and the air temperature door actuator for the following conditions:
Did you find and correct the condition? | -- | Go to Step 24 | |||||||||||||
9 | Test the ignition 3 voltage circuit of the air temperature door actuator for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 10 | ||||||||||||
10 | Test the ground circuit of the air temperature door actuator for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 11 | ||||||||||||
11 | Test the 5 volt reference circuit of the air temperature door actuator for an open, a high resistance, short to ground, or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 12 | ||||||||||||
12 | Test the air temperature door position signal circuit of the air temperature door actuator for an open, high resistance, short to ground, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 13 | ||||||||||||
13 | Test the air temperature door control circuit of the air temperature door actuator for an open, high resistance, short to ground, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 14 | ||||||||||||
Important:: The air temperature door actuator connector and the HVAC controller connector must be connected to correctly perform tests.
Does the air temperature door actuator drive shaft rotate and does the voltage change? | -- | Go to Step 15 | Go to Step 19 | |||||||||||||
15 |
Does the voltage measure near the specified value when increasing air temperature, near the specified value when decreasing air temperature and near the specified value when stationary? | 0 V increasing 5 V decreasing 2.5 V stationary | Go to Step 16 | Go to Step 21 | ||||||||||||
16 | Inspect the air temperature door for a mechanical failure or a condition that allows excessive travel of the door. Did you complete the repair? | -- | Go to Step 24 | -- | ||||||||||||
17 | Test the ignition 3 voltage circuit of the HVAC controller for an open, a high resistance or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 18 | ||||||||||||
18 | Test the ground circuit of the HVAC controller for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 21 | ||||||||||||
19 | Inspect for poor connections at the harness connector of the air temperature door actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 20 | ||||||||||||
20 | Inspect the air temperature door actuator, door and any attaching linkage for binding or a condition that prevents drive shaft rotation. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 22 | ||||||||||||
21 | Inspect for poor connections at the harness connector of the HVAC controller. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 23 | ||||||||||||
22 |
Important:: Perform the recalibration procedure for the air temperature door actuator. Replace the air temperature door actuator. Refer to Air Temperature Actuator Replacement . Did you complete the replacement? | -- | Go to Step 24 | -- | ||||||||||||
23 | Replace the HVAC controller. Refer to Heater and Air Conditioning Control Replacement . Did you complete the replacement? | -- | Go to Step 24 | -- | ||||||||||||
24 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 |