Troubleshooting Notes - IHKR3 (Automatic Climate Control System) From 10/90-On

^ Troubleshoot with the BMW DIAGNOSTIC SYSTEM or equivalent scan tool.
^ Battery charged, U-min = 12V
^ Fuses associated with the IHKR2/3 are OK.
^ The matching adapter must be used for testing and the IHKR2/3 must be connected such that it is fully operable. Defect codes may be stored by the control unit when it is disconnected and checked. The defect codes stored prior to testing must therefore be printed out.


^ Inputs (E) not stored in the defect code memory of the IHKR2/3 control unit:
Buttons, terminal 15, terminal 30, terminal 61, vehicle speed signal, diagnostic link RxD.

^ Outputs (A) not stored in the defect code memory of the IHKR2/3 control unit:
Function lights, diagnostic link TxD.

^ To ensure uniform initial conditions for defect monitoring and storage, the IHKR2/3 must be switched on with the air flow control wheel. It, despite the IHKR2/3 being switched on, the air flow control wheels shows "OFF" in the ^D^ Status list control wheels (function lights of program buttons do not light), check the voltage supply from the control unit to the control wheel potentiometers in the operating unit.


Substitute values for temperature sensors

Defective component Substitute value
Left heater sensor 55°C (131°F)
Right heater sensor 55°C (131°F)
Outside temperature sensor 0°C (32°F)
Evaporator sensor -5°C (23°F)
Interior temperature sensor 24°C (75°F)


Substitute values for control wheels

Defective component Substitute value
Left temperature control wheel 24°C (75°F)
Right temperature control wheel 24°C (75°F)
Air flow control wheel 50 %
Mixing air control wheel 50 %
Footwell slide regulator 50 %