Test Description
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
The number(s) below refer to the step number(s) on the diagnostic table.
- 3: Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
- 4: Determine if the Powertrain Control Module has set DTCs which may affect HVAC operation are present.
- 5: The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.
Diagnostic System Check - HVAC Systems - Manual
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Did you review A Diagnostic Starting Point - Heating, Ventilation and Air Conditioning? | Go to Step 2 | Go to Diagnostic Starting Point - Heating, Ventilation and Air Conditioning in Heating, Ventilation and Air Conditioning |
| 2 | Install a scan tool. Does the scan tool power up? |
Go to Step 3 | Go to Scan Tool Does Not Power Up in Data Link Communications |
| 3 |
|
Go to Step 4 | Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications |
| 4 | Select the Powertrain Control Module display DTCs function on the scan tool. Does the scan tool display any DTCs? |
Go to Step 5 | Go to Symptoms - HVAC Systems - Manual |
| 5 | Does the scan tool display any DTCs which begin with a "U"? | Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications | Go to Step 6 |
| 6 | Does the scan tool display any DTCs which begin with a "P" that are associated with the HVAC system? | Go to Diagnostic Trouble Code (DTC) List | Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 3.4 L |