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 from a customer complaint or condition through delivery of the vehicle.

This step covers all physical and visual inspections of interior and underhood components. Most problems can be detected by a thorough inspection. Failure to perform this step could result in wasted time and/or misdiagnosis. All preliminary checks must pass before proceeding further down the flow chart.

These tables will direct you to the appropriate service manual section based on conditions found during the preliminary checks. All information necessary to repair or replace a component is included in that components section.

To run an air conditioning performance test the vehicle must be set-up according to the service manual instructions. The instructions include refrigerant purity check, manifold gauge set installation, and controller settings. Improper vehicle set up will result in inaccurate pressure and temperature readings.

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 vehicle setup in a service environment. To find your system problem compare the performance test readings to the readings on the charts for your ambient temperature. When all pressure and temperature readings fall within the limits of a given chart use that chart to repair the vehicle.

Perform this test when a customers complaint is related to a certain driving condition such as stop and go traffic on a hot sunny day. This will verify proper system operation at road speed.