GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 GMC C Sierra - 2WD 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Air Recirculation Malfunction

Test Description

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

  1. This step tests for a inoperative mode actuator in one mode position(s) or in the wrong mode position(s).

    2.

  2. This step tests for a inoperative recirculation actuator in one mode position(s) or in the wrong mode position(s).

    3.

  3. This step tests for A/C system performance that is correct for the for the conditions at hand; that would mandate a state of automatic recirculation mode being active. Automatic recirculation mode will become active when the A/C high side pressure reaches 2206-2620 kPa (320-380 psi) and remain ON until the high side pressure drops below 1447-1861 kPa (210-270 psi). In automatic recirculation mode their will be no indication on the HVAC controller that the mode is active, the out side air (OSA) and recirculation (REC) switches and indicators will be inoperative on the HVAC controller.

    4.

  4. This step tests for a internally shorted A/C high pressure recirculation switch causing the automatic recirculation mode to be active.

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

DEFINITION: Air recirculation is inoperative or always on.

1

Did you review HVAC operation and perform the necessary inspections?

Go to Step 2

Go to Air Delivery Description and Operation

2

  1. Turn ON the ignition, with the engine OFF.
  2. Place the blower control to the highest mode position.
  3. Place the mode control to mode each position.

Does the mode actuator operate correctly for each mode position?

Go to Step 3

Go to Air Delivery Improper

3

  1. Place the mode control to the floor position.
  2. Press the REC switch ON.
  3. Press the OSA switch ON.

Does the air inlet actuator operate correctly for each mode position?

Go to Step 4

Go to Step 7

4

Perform the A/C system performance test. Refer to Diagnostic Trouble Code (DTC) List in HVAC.

Does the high side pressure reading indicate a problem in the A/C system to mandate operation in the automatic recirculation mode?

Go to Step 5

Go to Step 6

5

Repair or replace the failed component.

Did you complete the repair or replacement?

Go to Step 15

--

6
  1. Start the engine.
  2. Place the mode control to the vent position.
  3. Press the A/C switch ON.
  4. Press the REC switch ON.
  5. Press the OSA switch ON.

Does the recirculation actuator operate correctly for each mode position?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 7

7
  1. Verify the recirculation door is in the recirculation mode position.
  2. Disconnect the A/C high pressure recirculation switch connector.

Does the recirculation door move to the outside air mode position?

Go to Step 8

Go to Step 9

8

  1. Turn OFF the ignition.
  2. Measure for continuity through the A/C high pressure switch.

Is continuity present?

Go to Step 13

Go to Step 9

9

Test the secondary A/C refrigerant high pressure cut-out switch output signal circuit for 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 15

Go to Step 10

10

Test the recirculation door motor control circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 11

11

Inspect for poor connections at the PCM. 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 15

Go to Step 12

12

Replace and reprogram the VCM or PCM.

    • If equipped with a 4.3 L. Refer to Powertrain Control Module Replacement in Engine Controls - 4.3 L.
    • If equipped with a 4.8 L, 5.3 L, or 6.0 L. Refer to Powertrain Control Module Replacement in Engine Controls - 4.8 L, 5.3 L, and 6.0 L.

Did you complete the replacement?

Go to Step 15

--

13

Inspect for poor connections at the secondary A/C refrigerant high pressure switch. 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 15

Go to Step 14

14

Replace the A/C high pressure recirculation switch. Refer to Air Conditioning (A/C) High Pressure Switch Replacement in Heating, Ventilation and Air Conditioning.

Did you complete the replacement?

Go to Step 15

--

15

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2