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Test Description

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The number(s) below refer to the step number(s) on the diagnostic table.

  1. 3:  This step tests for a auxiliary blower motor that does not operate regardless of the desired blower motor speed.
  2. 4:  This step tests for a auxiliary blower motor that operates, yet does not accurately respond to the desired blower motor speed.
  3. 5:  This step tests for an inoperative auxiliary mode actuator in one mode position(s) or in the wrong mode position(s).
  4. 10:  The front auxiliary HVAC control assembly mode switch control circuit will normally vary between 0-12 volts.
  5. 16:  An incorrectly installed auxiliary mode actuator, damaged attaching linkage(s). Any mechanical repairs will not require the mode actuator-auxiliary to be replaced.
Air Delivery Improper - Auxiliary (W/Sunroof)

Step Action Value(s) Yes No
Schematic Reference:  HVAC Schematics  
DEFINITION: Air does not flow correctly from the auxiliary air distribution outlets.
1 Did you review the HVAC operation and perform the necessary inspections? - Go to Step 2  Go to SYMPTOM TESTS
2
  1. Turn ON the ignition, with the engine OFF.
  2. Place the IP HVAC control assembly to the rear position.
  3. Place the front auxiliary HVAC control assembly blower control in the OFF position.
Is the auxiliary blower motor OFF?		 - Go to Step 3  Go to Blower Motor Always On - Auxiliary (W/O Sunroof)  or Blower Motor Always On - Auxiliary (W/Sunroof or Heat Only) 
3  Place the front auxiliary HVAC control assembly blower control in each mode position.
Does the auxiliary blower motor operate at all?		 - Go to Step 4  Go to Blower Motor Inoperative - Auxiliary (W/Sunroof or Heat Only)  or Blower Motor Inoperative - Auxiliary (W/O Sunroof) 
4  Does the auxiliary blower motor operate correctly for each mode position? - Go to Step 5  Go to Blower Motor Malfunction - Auxiliary (W/Sunroof or Heat Only)  or Blower Motor Malfunction - Auxiliary (W/O Sunroof) 
5 
  1. Place the front auxiliary HVAC control assembly blower control in the high position.
  2. Place the front auxiliary HVAC control assembly mode control in each mode position.
Does the auxiliary mode actuator operate correctly for each mode position?		 - Go to TESTING FOR INTERMITTENT AND POOR CONNECTIONS Go to Step 6 
6 Test the ignition 3 voltage circuit of the front auxiliary HVAC control assembly for an open, a high resistance or a short to ground. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 19  Go to Step 7 
7 Test the ground circuit of the front auxiliary HVAC control assembly for an open. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 19  Go to Step 8 
8 Test the ignition 3 voltage circuit of the auxiliary mode actuator for an open or a high resistance. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 19  Go to Step 9 
9 Test the ground circuit of the auxiliary mode actuator for an open. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 19  Go to Step 10 
10 
  1. Measure the voltage from the auxiliary mode door control circuit at the auxiliary mode actuator to a good ground.
  2. Place the front auxiliary HVAC control assembly mode control in each mode position.
Does the voltage measure less than the specified value in each mode position?		 12 V Go to Step 11  Go to Step 12 
11 Does the voltage measure near the specified value in each mode position? 0 V Go to Step 13  Go to Step 15 
12 Test the auxiliary mode door control circuit for a short to voltage. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 19  Go to Step 14 
13 Test the auxiliary mode door control circuit for an open, a high resistance or a short to ground. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 19  Go to Step 14 
14 Inspect for poor connections at the harness connector of the front auxiliary HVAC control assembly. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS and CONNECTOR REPAIRS .
Did you find and correct the condition?		 - Go to Step 19  Go to Step 17 
15 Inspect for poor connections at the harness connector of the auxiliary mode actuator. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS and CONNECTOR REPAIRS .
Did you find and correct the condition?		 - Go to Step 19  Go to Step 16 
16 
  1. Test the auxiliary mode actuator, door and any attaching linkage for any binding.
  2. Inspect the ductwork for any debris that would prevent air to flow through the ductwork.
Did you find and correct the condition?		 - Go to Step 19  Go to Step 18 
17 Replace the front auxiliary HVAC control assembly. Refer to HVAC CONTROL ASSEMBLY - FRONT AUXILIARY (FRONT OVERHEAD CONTROL A/C ONLY) or HVAC CONTROL ASSEMBLY - FRONT AUXILIARY (FRONT OVERHEARD CONTROL HEAT & A/C) .
Did you complete the replacement?		 - Go to Step 19  -
18 Replace the mode actuator- auxiliary. Refer to MODE ACTUATOR - AUXILIARY (TAHOE/YUKON) or MODE ACTUATOR - AUXILIARY (SUBURBAN/YUKON XL) .
Did you complete the replacement?		 - Go to Step 19  -
19 Operate the system in order to verify the repair.
Did you correct the condition?		 - System OK Go to Step 2 
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