Temperature Regulation - Air Conditioning

TEMPERATURE REGULATION - AIR CONDITIONING







Discharge air temperature in the A/C mode is also controlled by the air blending flap. The rotary knob controls how much air passes through the heater core.

Compressor control is a function of the IHKS control module and the Engine Control Module (ECM). When the "snowflake" button is pressed, the ECM is signaled for idle stabilization; it then switches the compressor On by activating the control side of the compressor relay.

The ECM will switch the compressor Off when the IHKS control module senses that evaporator temperature has dropped to approximately 3°C (or under full load as with the previous ECM systems).

EVAPORATOR TEMPERATURE SENSOR







The evaporator temperature sensor is a long, thin probe which is inserted into the left side of the IHKS housing. The sensor is a Negative Temperature Coefficient (NTC) thermistor, whose resistance varies according to temperature.

The evaporator temperature sensor tip reaches several inches into the evaporator core, where an accurate measurement of the core's temperature can be obtained.

IHKS CONTROL MODULE







The IHKS control module is mounted on the

system housing:

- Z3 on driver's side
- 318ti on the passenger's side

The IHKS control module's scope of function is to monitor the evaporator temperature sensor signal and notity the ECM to switch off the compressor if the evaporator is close to freezing temperature (3°C).

EXPANSION VALVE







The expansion valve of the IHKS system is accessible from inside the vehicle in the passenger's footwell area.

To access the expansion valve, a housing cover must first be removed. The expansion valve is installed in the IHKS housing. Sound deadening putty is packed around the expansion valve to minimize noise. Remove the putty to access the mounting bolts.

When reinstalling the valve, make sure a sufficient quantity of putty is packed around the expansion valve to prevent a future noise complaint.