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Home >> Buick >> 2007 >> Lucerne CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 221 (HVAC Systems - Manual) >> Diagnostic Information and Procedures >> Too Hot in Vehicle - Auxiliary >> Test Description

Test Description

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The numbers below refer to the step numbers on the diagnostic table.

  1. 7:  The specified values are from the A/C System Performance Test.
  2. 8:  The functionality of the auxiliary air temperature drive shaft is questioned.
  3. 9:  The functionality of the auxiliary air temperature door control circuit of the auxiliary HVAC control module is questioned.
  4. 10:  This step questions the status of the air temperature door control signal communication between the front and auxiliary HVAC control module equipped in the Vehicle Entertainment System.
  5. 11:  This step checks for proper auxiliary air temperature actuator drive shaft movement.
  6. 12:  The value will vary between 0-255 counts during normal operation. The HVAC control module connector must be connected during this step. This checks for proper operation of the air temperature actuator door control circuit and the HVAC control module.
  7. 15:  The value will vary between 0-255 counts during normal operation. The HVAC control module connector must be connected during this step. This checks for proper operation of the air temperature actuator door control circuit and the HVAC control module.
  8. 16:  The auxiliary blower motor switch control circuit should not have continuity to ground when front auxiliary blower control switch is in any position except auxiliary control.
  9. 18:  The value will vary between 0-255 counts during normal operation. The HVAC control module connector must be connected during this step.
Too Hot in Vehicle - Auxiliary

Step Action Value(s) Yes No
Schematic Reference: HVAC Schematics 
Connector End View Reference: HVAC Connector End Views 
DEFINITION: Auxiliary air temperature cannot be adjusted from the auxiliary controls or the auxiliary heating is insufficient.
This table diagnoses vehicles equipped with the auxiliary HVAC control module.
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2 The auxiliary HVAC control module cannot request A/C compressor operation. An A/C request must be generated by the HVAC control module to provide cooled airflow through the auxiliary system.
Does the HVAC control module operate and provide sufficient heating?		 - Go to Step 3  Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
3
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Observe the DTC List in Vehicle DTC Information.
Does the scan tool display any DTC B0428, B0429, B0434, B3531, B3532 or B3782?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information Go to Step 4 
4
  1. Turn ON the ignition, with the engine OFF.
  2. Place the mode switch in any position except OFF.
  3. Place the auxiliary blower control in each speed position.
Does the auxiliary blower motor operate at all?		 - Go to Step 5  Go to Blower Motor Inoperative - Auxiliary 
5 Does the auxiliary blower motor operate in each speed position? - Go to Step 6  Go to Blower Motor Malfunction - Auxiliary 
6
  1. Start the engine.
  2. Place the blower motor switch in the maximum speed position.
  3. Place the mode switch in the Vent position.
  4. Press the A/C request switch.
  5. Place the temperature switch in the coldest position.
Does the A/C compressor operate?		 - Go to Step 7  Go to HVAC Compressor Clutch Does Not Engage 
7  Perform the A/C System performance test. Refer to Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning.
Did you find and correct the condition?		 - Go to Step 35  Go to Step 8 
8  Does the Auxiliary Too Hot in Vehicle condition happen only with the auxiliary HVAC control module? - Go to Step 11  Go to Step 9 
9  Does the Auxiliary Too Hot in Vehicle condition occur only when using the front HVAC control module? - Go to Step 15  Go to Step 10 
10  Does the Auxiliary Too Hot in Vehicle condition happen with both the front and auxiliary HVAC control modules? - Go to Step 17  Go to Too Hot in Vehicle 
11 
  1. Install a scan tool.
  2. Set the front HVAC auxiliary control blower motor switch to any setting except Auxiliary or OFF.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the Auxiliary Temp Door Motor Position.
  5. Place the front air temperature switch from the coldest position to the warmest position.
Does the value measured stay within the specified range with a smooth transition between COLD and HOT?		 0-255 Counts Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 12 
12 
  1. Install a scan tool.
  2. Set the front HVAC auxiliary blower motor switch control to any setting except Auxiliary or OFF.
  3. Disconnect the auxiliary air temperature actuator.
  4. Turn ON the ignition, with the engine OFF.
  5. Observe the Auxiliary Temp Door Motor Command.
  6. Place the front air temperature switch from the coldest position to the warmest position.
Does the value measured stay within the specified range with a smooth transition between COLD and HOT?		 0-255 Counts Go to Step 13  Go to Step 22 
13 Connect a test light between the auxiliary air temperature actuator door control circuit and the ground circuit of the auxiliary air temperature actuator.
Does the test light illuminate?		 - Go to Step 21  Go to Step 14 
14 Connect a test light between the auxiliary air temperature actuator door control circuit and a good ground.
Does the test light illuminate?		 - Go to Step 23  Go to Step 24 
15 
  1. Install a scan tool.
  2. Set the front HVAC auxiliary control blower motor switch to any setting except Auxiliary or OFF.
  3. Disconnect the auxiliary HVAC temperature and blower control within the vehicle entertainment system (VES).
  4. Turn ON the ignition, with the engine OFF.
  5. Observe the Auxiliary Temp Door Motor Command.
  6. Place the front air temperature switch from the coldest position to the warmest position.
Does the value measured stay within the specified range with a smooth transition between COLD and HOT?		 0-255 Counts Go to Step 16  Go to Step 26 
16 
  1. Place the front auxiliary blower motor switch to any position except Auxiliary or OFF.
  2. Connect a test lamp between the ignition 3 voltage circuit of the auxiliary blower motor between the underhood fuse block and auxiliary blower motor control circuit of the front HVAC control module.
Does the test lamp illuminate?		 - Go to Step 25  Go to Step 18 
17 Connect a test lamp between the ignition 1 voltage circuit of the front HVAC control module and a good ground.
Does the test lamp illuminate?		 - Go to Step 30  Go to Step 26 
18 
  1. Install a scan tool.
  2. With a scan tool observe the Auxiliary Temp Door Motor Command.
  3. Disconnect the auxiliary HVAC control module.
  4. Place the front auxiliary blower motor switch to the Auxiliary control position.
  5. Place the auxiliary air temperature switch from the coldest position to the warmest position.
Does the value measure within the specified range with a smooth transition between COLD and HOT?		 0-255 Counts Go to Step 19  Go to Step 26 
19
  1. Place the front auxiliary blower motor switch to the auxiliary control position.
  2. Connect a test lamp between the ignition 3 voltage circuit of the HVAC control module and the auxiliary blower motor control circuit of the front HVAC control module.
Does the test lamp illuminate?		 - Go to Step 26  Go to Step 20 
20 Connect test lamp between the ignition 3 voltage circuit of the auxiliary blower motor and a good ground.
Does the test lamp illuminate?		 - Go to Step 25  Go to Step 28 
21 Inspect the auxiliary air temperature door and the auxiliary air temperature actuator for the following conditions:
  • An incorrectly installed auxiliary air temperature actuator-Refer to Air Temperature Actuator Replacement - Auxiliary .
  • Broken or binding linkages or air temperature door
  • An obstruction that prevents the air temperature door from operating within its full range of motion
  • Missing seals to the air temperature door
  • Misaligned seals to the air temperature door

Did you find and correct the condition?		 - Go to Step 35  Go to Step 29 
22 Test the auxiliary air temperature door control circuit of the auxiliary air temperature actuator from the HVAC control module to the auxiliary air temperature actuator for the following conditions:
  • An open
  • High resistance
  • A short to ground
  • A short to voltage

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 35  Go to Step 25 
23 Test the ground circuit of the auxiliary air temperature actuator for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 35  Go to Step 29 
24 Test the auxiliary air temperature door control circuit of the auxiliary air temperature actuator from the HVAC control module to the auxiliary HVAC control module for the following conditions:
  • An open
  • High resistance
  • A short to ground
  • A short to voltage

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 35  Go to Step 30 
25 Test the rear auxiliary blower motor speed control circuit for short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 35  Go to Step 28 
26 Test the auxiliary air temperature common door control circuit between the front HVAC control module and splice 253 for the following conditions:
  • An open
  • High resistance
  • A short to ground
  • A short to voltage

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 35  Go to Step 28 
27 Test the rear auxiliary blower motor control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 35  Go to Step 30 
28 Test the ignition 3 voltage circuit of the auxiliary blower motor 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 35  Go to Step 30 
29 Inspect for poor connections at the harness connector of the auxiliary air temperature 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 35  Go to Step 32 
30 Inspect for poor connections at the harness connector of the HVAC control module. 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 35  Go to Step 33 
31 Inspect for poor connections at the harness connector of the auxiliary HVAC control module or Vehicle Entertainment System. 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 35  Go to Step 34 
32 Replace the auxiliary air temperature actuator. Refer to Air Temperature Actuator Replacement - Auxiliary .
Did you complete the replacement?		 - Go to Step 35  -
33 Replace the HVAC control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup and programming.
Did you complete the replacement?		 - Go to Step 35  -
34 Replace the auxiliary HVAC control part of the Vehicle Entertainment System, if equipped. Refer to Control Module References in Computer/Integrating Systems for replacement, setup and programming.
Did you complete the replacement?		 - Go to Step 35  -
35 Operate the system in order to verify the repair.
Did you correct the condition?		 - System OK Go to Step 2 
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