Hummer H2. Manual - part 1936

PCM Scan Tool Data List 

SCAN TOOL DATA DEFINITIONS 

A/C Switch  

The scan tool displays On/Off. The scan tool displays On when the A/C request switch is active. The scan 
tool displays Off when the A/C request switch is inactive. 

AC Permission  

The scan tool displays Withheld/Granted. The scan tool displays Granted when the HVAC control 
module determines that conditions for compressor clutch engagement are present. The scan tool displays 
Withheld when the HVAC control module determines that conditions for compressor clutch engagement 
are not present. 

AC Pressure Sensor  

Mode Switch

Input/Output

On/Off

Off

Off Switch

Input/Output

On/Off

Off

Outside Air Temp. Filtered Input/Output

° C/° F

22-27° C (70-

80° F)

Outside Air Temp. Raw

Input/Output

° C/° F

Varies

Pressure Cycle Switch

Input/Output

Low Pressure, Normal

Varies

Rear Defrost Switch

Input/Output

On/Off

Off

Recirculate Switch

Input/Output

On/Off

Off

RH AC Duct Actual

Sensor Data

Counts

Varies

RH AC Duct Desired

Sensor Data

Counts

Varies

RH Heater Duct Actual

Sensor Data

Counts

Varies

RH Heater Duct Desired

Sensor Data

Counts

Varies

Right Mix Door Actual

Door 

Positions

Counts

Varies

Right Mix Motor Drive

Door 

Positions

Stop, Increase, Decrease

Stop

Right Temp. Setting

Input/Output

° C/° F

Varies

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

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

F)

A/C Pressure Sensor

Engine Data 2

kPa/Psi

629-845 kPa (85-120 psi)

A/C Pressure Sensor

Engine Data 2

Volts

Varies

A/C Relay Command

Engine Data 2

On/Off

Varies

A/C Request Signal

Engine Data 2

Yes/No

Varies

ECT Sensor

Engine Data 2

° C/° F

92° C (197° F)

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

The scan tool displays 0-3450 kPa (0-500 psi). The voltage applied to the powertrain control module 
(PCM) input from the A/C refrigerant pressure sensor is converted to a pressure value. 

AC Pressure Sensor  

The scan tool displays 0-5 volts. The voltage applied to the PCM input for the A/C refrigerant pressure 
sensor. 

A/C Relay Command  

The scan tool displays On/Off. The scan tool displays the control decision for the compressor clutch relay 
output as determined by the PCM. 

A/C Request Signal  

The scan tool displays Yes/No. The scan tool displays Yes when the PCM receives a class 2 message 
from the HVAC control module to engage the A/C compressor clutch. The scan tool displays No when 
the PCM receives a class 2 message from the HVAC control module to disengage the A/C compressor 
clutch. 

Air Inlet Door Commanded  

The scan tool displays 0-255 counts. The scan tool displays the desired recirculation door position as 
determined by the HVAC control module. 

Air Inlet Door Actual  

The scan tool displays 0-255 counts. The voltage applied to the recirculation door position input of the 
HVAC control module is converted to a number between 0 and 255 where 51 Counts is approximately 
equal to 1 V. 

Air Inlet Motor Drive  

The scan tool displays Stop, Increase, or Decrease. The scan tool displays the control decision for the 
actuator output as determined by the HVAC control module. 

Air Mix Door Left Commanded  

The scan tool displays 0-255 counts. The scan tool displays the desired left air temperature door position 
as determined by the HVAC control module. 

Air Mix Door Right Commanded  

The scan tool displays 0-255 counts. The scan tool displays the desired right air temperature door position 
as determined by the HVAC control module.

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

Auto Switch  

The scan tool displays On/Off. The scan tool displays On when the automatic switch is active. The scan 
tool displays Off when the automatic switch is inactive. 

Battery Voltage  

The scan tool displays 0-25 volts. The voltage measured from the battery positive voltage circuit and the 
ground circuit of the HVAC control module. 

Blower Motor PWM Speed  

The scan tool displays 0-114%. The scan tool displays the control decision for the blower motor speed as 
determined by the HVAC control module. The scan tool displays 114% when the blower motor is 
commanded to maximum speed. The scan tool displays 0% when the blower motor is commanded OFF. 

Dim Level Requested  

The scan tool displays 0%-100%. This is the percentage of backlighting requested by the body control 
module. 

Engine Coolant Temp.  

The scan tool displays -39 to 140° C (-38 to 284° F). This is the engine coolant temperature sent to the 
HVAC control module by the PCM. 

ECT Sensor  

The scan tool displays -39 to 140° C (-38 to 284° F). The voltage applied to the PCM input from the 
engine coolant temperature sensor is converted to a temperature value. 

Fan Down Button  

The scan tool displays On/Off. The scan tool displays On when the fan down switch is active. The scan 
tool displays Off when the fan down switch is inactive. 

Fan Up Button  

The scan tool displays On/Off. The scan tool displays On when the fan up switch is active. The scan tool 
displays Off when the fan up switch is inactive. 

Front Defrost Switch  

The scan tool displays On/Off. The scan tool displays On when the defrost switch is active. The scan tool 
displays Off when the defrost switch is inactive.

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

Ign. Since Current DTC  

The scan tool displays 0-100 Cycles. The number of the ignition cycles since the setting of the most 
recent current diagnostic trouble code (DTC). 

Inside Air Temp Fan  

The scan tool displays On/Off. The scan tool displays the control decision for the fan motor output as 
determined by the HVAC control module. The fan motor is internal to the inside air temperature sensor 
assembly. 

Inside Air Temp.  

The scan tool displays -40 to 215° C (-40 to 419° F). The voltage applied to the HVAC control module 
input for the inside air temperature sensor is converted to a temperature value. 

Left Mix Door Actual  

The scan tool displays 0-255 counts. The voltage applied to the left air temperature door position input of 
the HVAC control module is converted to a number between 0 and 255 where 51 Counts is 
approximately equal to 1 V. 

Left Mix Motor Drive  

The scan tool displays Stop, Increase, or Decrease. The scan tool displays the control decision for the 
actuator output as determined by the HVAC control module. 

Left Solar Sensor  

The scan tool displays 0-255 counts. The voltage applied to the left sunload input of the BCM is 
converted to a number between 0 and 255 where 51 Counts is approximately equal to 1 V. 

Left Temp. Setting  

The scan tool displays 15 to 32° C (60 to 90° F). The scan tool displays the selected temperature from the 
left air temperature switch. 

LH AC Duct Actual  

The scan tool displays 0-255 counts. The voltage applied to the left upper duct air temperature input of 
the HVAC control module is converted to a number between 0 and 255 where 51 Counts is 
approximately equal to 1 V. 

LH AC Duct Desired  

The scan tool displays 0-255 counts. The desired value of the left upper duct air temperature input. The 

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2