GM Service Manual Online
For 1990-2009 cars only

Use the Scan Tool Data Display Values and Definitions in order to assist in diagnosing the HVAC. Compare the vehicles actual scan tool data with the typical data display value table information. Use the data information in order to aid in understanding the nature of the concern when the vehicle does not match with the typical data display values.

The scan tool data values were taken from a known good vehicle under the following conditions:

    • The ignition switch is in the ON position.
    • The engine is running at idle.
    • The vehicle is in PARK.
    • The doors are closed.
    • The windows are closed.
    • The A/C is ON.
    • The ambient air temperatures are at 22-27°C (70-80°F).

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Body Control Module (BCM)

Operating Conditions: Engine idling, A/C ON, ambient air temperature between 22-27°C (70-80°F)

A/C Request Switch

Inputs

On/Off

Varies

Powertrain Control Module (PCM)

Operating Conditions: Engine idling, A/C ON, ambient air temperature between 22-27°C (70-80°F)

A/C Disengage History 1,2,3, or 4

Engine Data

None, A/C Pressure, Engine Speed, Batt Voltage, Anti Stall, RPM Unstable, WOT, Launch Perf., Coolant Hot

None

A/C Pressure Disable

Engine Data

Yes/No

No

A/C High Side Pressure Sensor

Engine Data

Volts

Varies

A/C Off for WOT

Engine Data

Yes/No

Varies

A/C Relay Circuit History

Engine Data

OK/Open/Short

OK

A/C Relay Circuit Status

Engine Data

OK/Fault

OK

A/C Relay Command

Engine Data

On/Off

Varies

A/C Request Signal

Engine Data

Yes/No

Varies

Ambient Air Temperature

Engine Data

°C/°F

Varies

ECT Sensor

Engine Data

°C/°F

Varies

Ignition 1 Signal

Engine Data

Volts

Varies

Engine Control Module (ECM)

Operating Conditions: Engine idling, A/C ON, ambient air temperature between 22-27°C (70-80°F)

A/C Disengage History 1,2,3, or 4

Engine Data

None, A/C Pressure, Engine Speed, Batt Voltage, Anti Stall, RPM Unstable, WOT, Launch Perf., Coolant Hot

None

A/C Pressure Disable

Engine Data

Yes/No

No

A/C High Side Pressure Sensor

Engine Data

Volts

Varies

A/C Off for WOT

Engine Data

Yes/No

Varies

A/C Relay Circuit Status

Engine Data

OK/Fault

OK

A/C Relay Command

Engine Data

On/Off

Varies

A/C Request Signal

Engine Data

Yes/No

Varies

Ambient Air Temperature

Engine Data

°C/°F

Varies

ECT Sensor

Engine Data

°C/°F

Varies

Ignition 1 Signal

Engine Data

Volts

Varies