Specifications

97
Data Parameters Climate Control Parameters
BLOWER CONTROL
Range: ___________________________________________________________ 0 to 8V
The blower motor is controlled through an output stage often mounted in a heat sink on the
heater case. The control lead from the IHKA module supplies a varying voltage (2.0 to 8.0V)
based on the position of the blower control rocker switch. The blower speed increases through
the 15 steps until 8V is supplied to the control lead. At this point (the 16th step), the blower is
running at maximum speed. The speed of the blower fan is also influenced by the Y Factor and
the degree of heating or cooling power requested. When the IHKA system is switched ON, the
blower fan will come on at a speed that is dependent on the Y Factor and system settings. The
battery charge condition also contributes to blower speed. When the battery drops below 12V,
the blower speed signal to the blower output stage is reduced proportionately. To switch the
system off, the rocker switch must be stepped down to the lowest setting and then switched off.
Blower control operation is activated with the ignition switched on. The blower speed is
controlled by regulating (varying) the ground circuit. The IHKA control module determines the
appropriate blower speed using the following primary inputs:
• Blower control thumbwheel/rocker switch inputs
• The Y Factor
On some models, the requested blower speed selection is monitored by the control module
which is remotely mounted. On all other models, the requested input selection for blower speed
is internally monitored because the control panel and control module are combined.
COMPRESSOR SHUTOFF SIGNAL
Range: __________________________________________________________ ON/OFF
The IHKA module monitors the full load input from the ECM. If the ECM detects “full load”
conditions, it signals the IHKA control module to disengage the A/C compressor.
Some of the conditions for compressor shutoff may be:
• Vehicle speed less than 10 MPH (16 KPH)
• Throttle is wide open
• Engine coolant temperature has reached a maximum temperature
The compressor may be turned off for a maximum of 4 minutes (actual duration may differ
between systems).
COOLANT(°)
Range: _________________________________________ –40 to 199°C or –40 to 389°F
These parameters indicate the engine coolant temperature (ECT) based on the ECT sensor
signal sent over the K Bus communication line to the IHKA controller. The substituted default
value most often used is 212°F (100°C).
COOLANT VALVES
COOLANT VALVE LEFT
Range: ___________________________________________PWM-controlled 0 to 100%
COOLANT VALVE RIGHT
Range: ____________________________________________________ OPEN/CLOSED
COOLANT VALVE ON(ms)
Range: ______________________________________________________ not available
The coolant valves are electrically controlled and may be pulse-width modulated by the climate
control module to control heater core temperature. At 100% duty cycle, or fully powered up, the
valves are in the closed position preventing coolant flow into the heater core. Usually, the valves
are spring-loaded to the open position. Valve control is dependent on system voltage, driver