Step 1 - Preliminary Checks

IMPORTANT THE INFORMATION CONTAINED IN THE CHARTS CAN GIVE A INDICATION OF A SYSTEM FAULT, HOWEVER AN INCORRECT DIAGNOSIS OF THE SYSTEM IS POSSIBLE.


Diagnostic Flow Chart

This chart is the starting point for verifying and diagnosing all air conditioning and HVAC control related complaints. It represents the correct path to follow in response to a customer complaint.

Preliminary Checks

This step covers all physical and visual inspections of interior and underhood components. Many problems can be detected by thorough inspection. Failure to perform this step could result in wasted time proceeding further down the flow chart.

Vehicle Set-Up and Performance Test

To run an air conditioning performance test the vehicle must be set-up according to the service manual instructions. Improper vehicle set-up will result in inaccurate pressure and temperature readings.

General and Specific System Condition Charts

These charts were developed in a wind tunnel by producing known system problems and recording pressures and temperatures at various ambient temperatures. The tests were then validated using the same vehicles set-up in a service environment. To find your system problem, compare the performance test readings to the readings on the charts for your ambient temperature. There is some variance in readings between systems of diggerent vehicles, however, the target areas have been developed to accommodate these changes.

Compressor Control Test

This is designed to evaluate the compressor's ability to change displacement with varying heat loads.

Step 1 - Preliminary Checks

Repair the following as necessary. If discharge temperature with A/C on is normal after making the following repairs, the system is operating properly.

^ Connect Tech 2. Check for diagnostic codes, if codes are found refer to Computers and Control Systems.
^ A/C fuse.
^ A/C blower operation.
^ Temperature door. Move temperature door dial rapidly from hot to cold. Listen for change in airflow or temperature door hitting at each end. Correct as necessary.
^ A/C compressor clutch coil connection.
^ A/C pressure transducer connection.
^ A/C compressor belt. Replace if damaged or missing.
^ Engine cooling fan operation (at idle, cooling fan must be on at any A/C mode, except 3.1L/V6 engines) cooling fan must be operating in correct direction (drawing outside air through the condenser toward engine).
^ Condenser - Check for restricted air flow.
^ Dealer technical bulletins for updates on A/C system.