GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC C Sierra - 2WD 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Air Recirculation Malfunction

Test Description

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

  1. This step tests for a inoperative mode actuator in one mode positions or in the wrong mode positions.

    2.

  2. This step tests for a inoperative recirculation actuator in one mode positions or in the wrong mode positions.

    3.

  3. This step tests A/C system performance that is correct for the current conditions. that would mandate a state of automatic recirculation mode being active. The automatic recirculation mode becomes active when the A/C high side pressure reaches 2206-2620 kPa (320-380 psi). The mode remains ON until the high side pressure drops below 1447-1861 kPa (210-270 psi). In automatic recirculation mode the HVAC controller does not indicate that the mode is active. The outside air (OSA) and the recirculation (RECIRC) switches and indicators are inoperative on the HVAC controller.

    4.

  4. This step tests for an A/C high pressure recirculation switch, which is internally shorted and which causes 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 perform the HVAC diagnostic system check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2

  1. Turn ON the ignition, with the engine OFF.
  2. Place the blower motor switch in the maximum speed position.
  3. Place the mode switch in 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 switch in the floor position.
  2. Place the recirculation switch in the ON position.
  3. Place the outside air switch in the ON position.

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 Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning.

Does the high side pressure reading indicate a condition in the A/C system which requires 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. Place the A/C request switch in the ON position.
  4. Place the recirculation switch in the ON position.
  5. Place the outside air switch in the ON position.

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 connector to the A/C high pressure recirculation switch.

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 output signal circuit on the high pressure cut-off switch of the secondary A/C refrigerant unit for a high resistance or for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 10

10

Test the motor control circuit on the recirculation door 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 15

Go to Step 11

11

Inspect for poor connections at the PCM. 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 15

Go to Step 12

12

Replace and reprogram the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L, or to Powertrain Control Module Replacement in Engine Controls-8.1L.

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 to 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 Recirculation 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