1. Reconnect any previously disconnected components.
2. Visually inspect all of the HVAC and the HVAC-related components and wiring. Refer to General Electrical Diagnosis in Wiring Systems.

Did you find any problems during the visual inspection?

--

Go to Step 2

Go to Step 3

Repair the problem(s) as necessary.

Is the repair complete?

--

Go to Step 3

--

1. Connect the scan tool to the data link connector (DLC).
2. Turn the ignition switch from the OFF position to the ON position. Do not start the engine.
3. Allow the HVAC system 40 seconds to initialize before attempting communication.

Does the scan tool communicate with the electronic climate control (ECC) module?

--

Go to Step 5

Go to Step 4

Does the scan tool communicate with any other modules on the Class 2 data line?

--

Go to Scan Tool Does Not Communicate with Heater and Air Conditioning (A/C) Control in Data Link Communications

Go to Scan Tool Does Not Communicate with Class 2 Data Line in Data Link Communications

Use the scan tool in order to read the HVAC diagnostic trouble codes (DTCs).

Does the scan tool display any current DTCs?

--

Go to DTC Table

Go to Step 6

Are any history DTCs stored in the memory?

--

Go to Step 7

Go to HVAC System Check

1. Consult the appropriate DTC table for the history DTC.
2. Read the following sections:

•	Diagnostic Aids

•	Conditions for Setting the DTC

3. Operate the A/C system for several minutes while monitoring a scan tool for HVAC DTCs.

Did any DTC set as a current DTC while you were monitoring the scan tool?

--

Go to DTC Table

Go to HVAC System Check