1

Did you perform the HVAC diagnostic system check?

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Go to Step 2

Go to Diagnostic System Check

1. Ensure that the A/C system pressures are normal.
2. Idle the engine at the normal operating temperature.
3. Turn the A/C ON.

Is the A/C clutch engaged?

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Go to Step 3

Go to Step 10

With the engine idling, connect the Scan Tool.

Does the Scan Tool display the A/C request NO?

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Go to Step 4

Go to Step 5

Refer to Diagnostic Starting Point in Engine Controls - 4.6L.

Is the repair complete?

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Go to Diagnostic System Check

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Verify the following Scan Tool readings:

1. OUTSIDE TEMP is close to ambient temperature if the car is moving at highway speeds.
2. EVAP INLET TEMP is above the specified value.

Do the sensors read OK?

-12°C

(10°F)

Go to Step 6

Go to Step 7

Replace the heater and A/C programmer. Refer to Programmer Replacement

Is the repair complete?

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Go to Diagnostic System Check

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Inspect for additional resistance in the sensor wiring caused by a poor connection (loose, corroded).

Is the sensor wiring OK?

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Go to Step 8

Go to Step 9

Replace the sensor. Refer to Ambient Temperature Sensor Replacement

Is the repair complete?

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Go to Diagnostic System Check

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Repair the resistance to the sensor wiring. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Diagnostic System Check

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Turn the A/C ON.

Does the A/C relay cycle?

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Go to Step 16

Go to Step 11

1. Remove the A/C relay.
2. Inspect the coil resistance of the A/C relay between relay pin C3 and relay pin D1.

Is the coil resistance within the specified values?

70ohms-150ohms

Go to Step 12

Go to Step 15

Inspect the voltage between harness pin D1 and ground.

Is the measured voltage near battery voltage?

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Go to Step 13

Go to Step 14

Repair the open in the following components:

Is the repair complete?

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Go to Diagnostic System Check

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Repair the open in CKT 459. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Diagnostic System Check

Go to Diagnostic Starting Point in Engine Controls - 4.6L.

Replace the relay.

Is the repair complete?

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Go to Diagnostic System Check

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1. Remove the A/C relay.
2. Jump the A/C Compressor Relay connector circuit D3 to C1.

Does the clutch engage?

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Go to Step 17

Go to Step 18

Replace the A/C relay.

Is the repair complete?

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Go to Diagnostic System Check

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18

With the jumper still connected, jump the A/C Compressor Relay pins C1 to D1.

Does the clutch engage?

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Go to Step 19

Go to Step 20

Repair the open in CKT 2340 or replace the A/C compressor fuse. If the fuse is blown, inspect for a short to ground.

Is the repair complete?

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Go to Diagnostic System Check

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With the jumper still connected, inspect the voltage at pin A of the compressor clutch.

Is the voltage equal to the battery voltage?

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Go to Step 22

Go to Step 21

Repair the open in CKT 59.

Is the repair complete?

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Go to Diagnostic System Check

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22

Inspect the continuity from pin B of the compressor clutch connectors to ground.

Is the continuity continuous?

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Go to Step 23

Go to Step 26

Inspect the A/C compressor clutch coil diode for a short.

Is there a short?

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Go to Step 24

Go to Step 25

Fix the short. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Diagnostic System Check

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Replace the compressor clutch coil. Refer to Compressor Clutch Plate and Hub Assembly Removal (HT6/HD6)

Is the repair complete?

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Go to Diagnostic System Check

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Repair the open in CKT 350. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Diagnostic System Check

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