With HVAC System - Automatic

Diagnostic Codes:

Symptom Chart:

SYSTEM DIAGNOSIS

- Do the Diagnostic Test(s) listed next to your symptom in the Symptom Table. Code symptoms must be diagnosed first.

On-board Diagnostics (Part 1):

On-board Diagnostics (Part 2):

On-board Diagnostics (Part 3):

ON-BOARD DIAGNOSTICS

The C68 Electronic Air Conditioning System is equipped with on-board diagnostics. The diagnostics feature displays fault codes, system data parameters, and clears codes. It also commands some HVAC Programmer outputs. When a code is set, the temperature (external or set) will flash during the first two minutes of operation. When in diagnostic mode, pressing AUTO at any time terminates the diagnostic mode. Refer to images for procedures.

SCAN TOOL DIAGNOSTICS

The C68 Electronic Air Conditioning System has the ability to employ bi-directional scan tool diagnostics. The diagnostics feature displays fault codes, system data parameters, and clears codes. It also commands some HVAC Programmer outputs and allows for snap shot and control head monitoring. When a code is set, the temperature (external or set) will flash during the first two minutes of operation. The scan tool offers advantages over the on-board diagnostics because the same faults that disable HVAC functions may disable the on-board diagnostics.

NOTE ON HISTORY CODES

Intermittent Faults

If the code set is a history code there is a good chance that the problem is intermittent or no longer exists. If the fault is intermittent, the diagnostics on the following pages will not be effective in locating the fault. In most cases the fault must be present to locate the problem. Most intermittent problems are caused by faulty electrical connections or wiring. When an intermittent fault is encountered check for:

- Poor mating connector halves or terminals not fully seated in the connector body (backed out).

- Improperly formed or damaged terminals. All connector terminals in a problem circuit should be carefully reformed to increase contact tension.

- Poor terminal to wire connection. This requires removing the terminal from the connector body to inspect.