Diagnosis for the temperature control portion of this system is based on malfunction codes stored in the heater-A/C control. When a code has been set, the man symbol on the RH side of the heater-A/C control display will flash.

The CJ2 air conditioning is equipped with an on-board diagnostic feature which allows the heater-A/C control to detect certain system faults. The diagnostic feature can also be used to display certain data parameters. If the heater-A/C control detects a fault in the system, the man symbol will flash during the first 2 minutes of vehicle operation.

Entry into the diagnostic mode is gained by pressing in on both temperature knobs at the same time for 5 seconds. The following display modes are found within diagnostics:

By rotating the driver temperature knob one detent in either direction, the display is toggled between pointer and value. The value displayed is the decimal equivalent of the RAM contents. A 2 is formed using the minus sign and the leading 1 in order to display values over 199.

A diagnostic pointer mode is identified by a minus sign preceding the pointer number. The pointer provides an index, which identifies the corresponding diagnostic value. The Diagnostic Trouble Codes (DTCs) reside under diagnostic pointer -00. The pointer will be set to this position upon initial entry into diagnostics. If more than one code exists, they will be displayed sequentially at a rate of 2 seconds per fault. Rotating the passenger temperature knob will switch the diagnostic pointers. A wrap around feature is provided if the pointer is continued past either end. Other data used by the computer resides under different diagnostic pointers, and may not be of use in observing the system. To exit the diagnostic mode, press any mode button.

Important: A two-digit trouble code indicates the fault is current. A three-digit trouble code indicates a history fault.

For a list of Trouble Codes and their meanings, refer to DTC Table .

To clear codes from the heater-A/C control, press the A/C mode button.

Any of the following components may cause malfunction in the temperature controls:

As a part of the diagnostic process Inspect the following components:

•	The blower controls. Refer to Cell: 66 .

•	The compressor controls. Refer to Cell: 67 .

•	The air delivery controls. Refer to Cell: 68 Heater A/C Control .