Substitute Value Operation

IHKR1 SUBSTITUTE VALUE OPERATION

If an input potentiometer or sensor (or its circuit) fails, the control module will ignore the faulty input. In its place, the module will use a substitute value which has been programmed into its memory for just this purpose. The substitute value, typically a mid-scale value for a particular input, allows the IHKR system to operate as normally as possible, despite the fault.

Substitute values for IHKR1 components are:
Desired temperature potentiometer (left or right) 75 °F (24 °C)
Interior temperature sensor 75 °F (24 °C)
Ambient temperature sensor 32 °F (0 °C)
Heater core temperature sensor (left or right) 130 °F (55 °C)
Evaporator temperature sensor 23 °F (-5 °C) *
Blower speed potentiometer 50%
Temperature mixing potentiometer 50%
Footwell flap potentiometer 50%

* The substitute value for the evaporator temperature sensor is well below the A/C compressor cycling point (1-3 °C). Therefore, if the evaporator temperature sensor signal is not plausible, the substitute value will switch the refrigeration system off.