Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

Did you review the Air Delivery Description and Operation and the Air Temperature Description and Operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - HVAC Systems - Manual

1. Start the engine.
2. Turn the blower switch to any position except OFF.
3. Press the A/C switch to the ON position.

Does the A/C compressor clutch engage?

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

Go to Step 3

1. Connect a scan tool.
2. Use the scan tool to command the A/C compressor clutch relay ON. When the relay is energized the cooling fan will also run at low speed.

Does the A/C compressor clutch engage?

Go to Step 8

Go to Step 4

1. Exchange the A/C compressor clutch relay with a known good relay (the horn relay).
2. Use the scan tool to command the A/C compressor clutch relay ON.

Does the A/C compressor clutch engage?

Go to Step 16

Go to Step 5

Test the A/C compressor clutch supply voltage circuit for an open 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 27

Go to Step 6

1. Remove the A/C compressor clutch relay from the underhood fuse block.
2. Start the engine and turn the blower switch to any position except OFF.
3. Test for supply voltage to the A/C compressor clutch relay at cavities 1 and 5. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 27

Go to Step 7

Test the A/C compressor clutch relay control circuit for an open or a short to B+. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 27

Go to Step 20

Test the A/C switch supply voltage circuit for an open 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 27

Go to Step 9

Test the A/C request circuit for an open 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 27

Go to Step 10

1. Start the engine.
2. Turn the blower switch to any position except OFF.
3. Press the A/C switch to the ON position.
4. Measure the voltage at cavity 9 of the A/C Switch. The voltage should be 12.5 volts.

Is the measured voltage within specification?

Go to Step 11

Go to Step 18

Measure the resistance of the A/C resistor. The resistance should be 2.2K ohms.

Is the measured resistance within specification?

Go to Step 12

Go to Step 25

Test the A/C resistor feed and ground circuits for an open, a short to ground and for a short to B+. Any one of these conditions will cause the A/C system to be inoperative. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 27

Go to Step 13

Did you find and correct the condition?

Go to Step 27

Go to Step 14

Test the refrigerant pressure switch ground circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems and Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement .

Did you find and correct the condition?

Go to Step 27

Go to Step 15

Test the refrigerant pressure switch. The switch should be normally closed between terminals 1 and 4.

Did the switch test OK?

Go to Step 20

Go to Step 19

Inspect for a poor connection at the harness connector of the A/C compressor clutch relay. 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 17

Go to Step 21

Inspect for a poor connection at the harness connector of the A/C compressor clutch. 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 27

Go to Step 22

Inspect for a poor connection at the harness connector of the A/C 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 27

Go to Step 23

Inspect for a poor connection at the harness connector of the refrigerant 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 27

Go to Step 24

Inspect for a poor connection at the harness connector of the powertrain control module (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 27

Go to Step 26

Replace the A/C compressor clutch relay. Refer to Compressor Relay Replacement .

Did you complete the replacement?

Go to Step 27

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Replace the A/C compressor clutch. Refer to Air Conditioning Compressor Replacement

Did you complete the replacement?

Go to Step 27

--

Replace the A/C switch. Refer to Heater and Air Conditioning Control Replacement .

Did you complete the replacement?

Go to Step 27

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Replace the refrigerant pressure switch. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement

Did you complete the replacement?

Go to Step 27

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Replace the A/C resistor.

Did you complete the replacement?

Go to Step 27

--

Replace the PCM. Refer to Powertrain Control Module Programming and Setup in Programming and Setup.

Did you complete the replacement?

Go to Step 27

--

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3