Specifications

96
Data Parameters Climate Control Parameters
Climate Control Parameters
AIRCO SWITCH
AIRCO CLUTCH (AIRCO COMPRESSOR CLUTCH)
AIRCO REQUEST 1
AIRCO REQUEST 2
AIRCO ENABLE
Range: __________________________________________________________ ON/OFF
These parameters indicate either the switch and request status of the A/C button (snowflake
button) located on the climate control faceplate, or the A/C compressor clutch and system status.
The Airco switch pushed in is only a request for A/C COMPRESSOR ACTIVATION. The request
signal (two requests if double control set) is sent from the climate control module to the ECM. On
some systems, the ECM has the option to cancel the request. On other systems, the ECM
decides to activate or not activate the A/C compressor. If the Airco or snowflake switch is on at
engine startup, the compressor clutch activation is delayed until engine speed exceeds 600 RPM
for at least 5 seconds. If the switch is turned off while the engine is running, the control module
continues to cycle the compressor with increasingly longer off-times for up to 15 minutes (unless
defrost is selected, which keeps the A/C on).
AUC FUNCTION
Range: ___________________________________________________ ACTIVE/INACTV
This parameter displays the status of the automatic recirculated air control (AUC) sensor.
AUC SENSOR(V)
Range: ______________________________________________________ not available
Automatic recirculated air control (AUC) is an additional feature controlling the automatic
operation of recirculated air. The AUC feature uses an oxidizable gas sensor usually mounted
behind the right side of the radiator or the right side upper portion of the fan shroud (samples air
quality as coolant fan pulls across the radiator). The AUC sensor contains a combined heating
element (powered by the IHKA module) and a gas sensor. The gas sensor requires heating to
work efficiently. The sensor produces a varying voltage based on air quality (concentration of
hydrocarbons, NOX, SOX, and CO). The voltage increases as the air becomes more polluted.
After it reaches a preset value, the IHKA closes the fresh air flaps. To prevent glass fogging, the
system has built-in time limits: 3 minutes when heating and 12 minutes when cooling. With
normal air quality, the AUC sensor reads about 0.5V. If the AUC sensor voltage increases to
3.0V, the ventilation or fresh air flaps will close (0%). At about 2.5V, the fresh flaps will read about
20% and 100% (fully open) at 2.4V.
BACK PRESSURE VALVE MOTOR (RAM AIR PRESSURE COMPENSATION)
Range: _________________________________________________________ 0 to 100%
The air volume entering the IHKA system is compensated for at higher vehicle speeds. In the
fresh air mode, the flaps are open 100% up to a road speed of approximately 37 MPH (60 KPH)
at which point they are closed to 40%. When the vehicle speed reaches about 55 MPH (90 KPH)
the flaps close to 30%. There is a hysteresis (overlap) built into the flap closing so that the flaps
will not oscillate open/closed at one set speed.
BLOWER(%)
Range: ______________________________________________________ not available
This parameter indicates the IHKA command position for the blower motor. At 0%, the blower
motor should be off, and at 100%, fully on. The climate control module determines the
appropriate blower speed based on the blower control manual switch input and the Y Factor (see
“Y FACTOR(%)” on page 100 for an explanation of the Y Factor).