Major Changes From IHKR1

IHKR2 MAJOR CHANGES FROM IHKR1

- The control panel, while very similar in appearance to the IHKR1 part (face view), is completely revised.
- Control panel push-buttons for rear window defroster, A/C compressor, and recirculating air functions have LED "On" indicators.
- The housing assembly is modified, especially the heater cores area and the drains.
- The footwell flaps and rear floor heat flaps (previously separate and connected by linkage) are combined into one flap (on each side) and are operated by a bowden cable, not stepper motors.
- Blower speed control is radically different; the motor is hard-wired to ground and speed is varied by applying different voltages to the motor.
- The final stage unit is replaced by a switch and resistor pack
- Stepper motors do not operate after system shutdown.
- Control modules produced from 5/90 on are codeable.
- A new compressor control system was introduced during the IHKR2 production period, on the 1991 525i (M50). In this system, the engine control module has more authority regarding compressor control.