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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 587 (HVAC SYSTEMS - MANUAL)DIAGNOSTIC INFORMATION AND PROCEDURESAIR RECIRCULATION MALFUNCTIONTEST DESCRIPTION
1999 GMC Forward Control 5.7 R, Automatic

Test Description

1999 GMC Forward Control 5.7 R, AutomaticSECTION Test Description
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

  1. 9:  The HVAC control module is supplied by 2 ignition-3 voltage circuits. Test the ignition-3 voltage circuit that does not supply the blower motor switch.
Air Recirculation Malfunction

Step Action Yes No
Schematic Reference: HVAC Schematics 
Connector End View Reference:  HVAC Connector End Views  
DEFINITION: Air recirculation is inoperative or is always ON.
1 Did you perform the HVAC Diagnostic System Check? Go to Step 2  Go to Diagnostic System Check - HVAC Systems - Manual 
2
  1. Turn ON the ignition, with the engine OFF.
  2. Place the blower motor switch at the maximum speed position.
  3. Place the mode switch in the vent position.
  4. Place the recirculation switch in the ON position.
  5. Observe the recirculation door.
  6. Place the ambient air switch in the ON position.
Does the recirculation door move from the recirculation to the outside air position?		 Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 3 
3 Except for the blower motor speed, are all of the functions of the HVAC control module inoperative? Go to Step 9  Go to Step 4 
4
  1. Turn OFF the ignition.
  2. Disconnect the recirculation actuator.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition-3 voltage circuit of the recirculation actuator with a test lamp that is connected to a good ground.
Does the test lamp illuminate?		 Go to Step 5  Go to Step 15 
5 Test the ground circuit of the recirculation actuator for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 18  Go to Step 6 
6
  1. Reconnect the recirculation actuator.
  2. Disconnect the HVAC control module.
  3. Observe the recirculation door.
  4. Connect a 3 amp fused jumper between the recirculation door control circuit and the ground circuit.
Does the recirculation door move into the outside air position?		 Go to Step 14  Go to Step 7 
7 Test the door control circuit of the recirculation actuator for an open, for a high resistance, for a short to ground, or for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 18  Go to Step 8 
8 Inspect the recirculation door and the recirculation actuator for the following conditions:
  • A misaligned recirculation actuator

    Refer to Recirculation Actuator Replacement .

  • Broken or binding linkages or recirculation door
  • An obstruction that prevents the recirculation actuator from operating within the full range of motion
  • Missing seals to the recirculation door
  • Misaligned seals to the recirculation door

Did you find and correct the condition?		 Go to Step 18  Go to Step 13 
9  Test the ignition 3 voltage circuit of the HVAC control module for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 18  Go to Step 10 
10 Test the battery positive voltage circuit of the HVAC control module for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 18  Go to Step 11 
11 Test the ground circuit of the HVAC control module for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 18  Go to Step 12 
12 Test the off blower motor control circuit of the HVAC control module for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 18  Go to Step 14 
13 Inspect for bad connections at the harness connector of the recirculation actuator. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 18  Go to Step 16 
14 Inspect for bad connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 18  Go to Step 17 
15 Repair the ignition 3 voltage circuit of the recirculation actuator. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 18  -
16 Replace the recirculation actuator. Refer to Recirculation Actuator Replacement .
Did you complete the replacement?		 Go to Step 18  -
17 Replace the HVAC Control module. Refer to HVAC Control Module Replacement (Buick)  or HVAC Control Module Replacement (Pontiac) .
Did you complete the replacement?		 Go to Step 18  -
18 Operate the system in order to verify the repair.
Did you correct the condition?		 System OK Go to Step 3 
RENDER: 1.0x

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