Preliminary Diagnosis

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

PRELIMINARY CHECKS
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.
Preliminary Checks - HVAC

COMPLAINT-CONDITION TABLES
These tables will direct you to the appropriate service procedure based on conditions found during the preliminary checks.
Testing and Inspection

VEHICLE SET UP/PERFORMANCE TEST
To run an air conditioning performance test the vehicle must be set-up according to instructions. The instructions include manifold gauge set installation and controller settings. Improper vehicle set up will results in inaccurate pressure and temperature readings.
Manifold Gauge Installation

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 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.
General, Normal & Specific System Condition Charts

PERFORMANCE TEST AT 72 KM/H (45 MPH)
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.