Has the HVAC Diagnostic System Check been performed?

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Go to Step 2

Go to Diagnostic System Check

1. Install a scan tool.
2. Start the engine and allow to idle in park.
3. Display the HVAC scan tool data list.
4. Switch the HVAC control assembly through the following operating modes:

•

Upper

•

Bi-Level

•

Lower

•

Defog

•

Defrost

•

Fresh Air

•	Recirculate

Does the scan tool indicate the correct combination of vacuum/electric solenoids ON and OFF (shown in the table below) through all of the operating modes listed?

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Go to Step 3

Go to Step 12

1. Disconnect the vacuum line connector to the HVAC control solenoid valve.
2. Connect a vacuum gauge to the purple vacuum line.
3. Start the engine and allow to idle in park.

Is the vacuum reading within the specified values?

10-17 in.Hg

Go to Step 5

Go to Step 4

Inspect and repair the leak or restriction in the purple vacuum supply line, vacuum tank, or the manifold vacuum line to the tank.

Is the repair complete?

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Go to Step 13

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1. Connect a hand vacuum pump to each of the vacuum actuator supply lines at the control solenoid valve connector.
2. Apply vacuum to each of the vacuum actuators.
3. Listen for door movement within the HVAC module assembly.

If necessary turn the ignition ON and and blower motor to HIGH in order to verify door operation.

Do the vacuum actuators hold vacuum and effectivly control door operation?

--

Go to Step 7

Go to Step 6

Inspect and repair or replace any sticking or binding door conditions, inoperative vacuum actuators, or vacuum supply lines. Refer to the following procedures:

Is the repair complete?

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Go to Step 13

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1. Disconnect the HVAC control solenoid valve electrical connector.
2. Connect a test light from the voltage supply circuit 41 terminal to ground.
3. Turn the ignition ON.

Does the test light illuminate?

--

Go to Step 9

Go to Step 8

Repair the open or high resistance in the voltage supply circuit 41.

Is the repair complete?

--

Go to Step 13

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1. Connect a test light from the voltage supply circuit 41 terminal to the following solenoid control circuit terminals:

•	Defroster solenoid (circuit 1396)

•	Heater solenoid (circuit 1397)

•	Mode closed solenoid (circuit 66)

•	Air inlet solenoid (circuit 1394)

•	Mode open solenoid (circuit 1395)

2. Switch the HVAC control assembly through all the operating modes listed in the table below.

Does the test light illuminate only when the table below indicates each solenoid control circuit should be ON.

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Go to Step 11

Go to Step 10

Test and repair the inoperative solenoid control circuits for the following conditions:

Did you find and correct the condition?

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Go to Step 13

Go to Step 11

Replace the HVAC control solenoid valve. Refer to Vacuum Electrical Solenoid Replacement .

Is the repair complete?

--

Go to Step 13

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Replace the HVAC control assembly. Refer to Control Assembly Replacement .

Is the repair complete?

--

Go to Step 13

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1. Clear any DTCs which may have set. Refer to Diagnostic Trouble Code (DTC) Clearing .
2. Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Diagnostic System Check

Upper

OFF

ON

OFF

N/A

ON

Bi-Level

OFF

ON

OFF

N/A

OFF

Lower

OFF

ON

ON

N/A

OFF

Defog

OFF

OFF

ON

OFF

OFF

Defrost

ON

OFF

ON

OFF

OFF

Fresh Air

N/A

N/A

N/A

OFF

N/A

Recirculate

N/A

N/A

N/A

ON

N/A