Specifications

Testing Testing Climate Control Systems

4.6 Testing Climate Control Systems

The scan tool can read Codes & Data from BMW climate control systems (Airco). Table 4-13 lists

BMW climate control systems.

4.6.1 Types of Climate Control Systems

BMW climate control systems are either fully manual, semiautomatic, or fully automatic. BMW

refers to these systems as IHKS (manual), IHKR (semiautomatic) and IHKA (fully automatic). IHK

translates from German into “integrated heating and air conditioning system.”

• IHKR—standard equipment, semiautomatic heating and air-conditioning system. This system

is single zone, regulating temperature based on a manually-selected temperature. Blower

control, air distribution, and flap positions are all manually operated.

• IHKA—is fully automatic and may have dual controls for driver and passenger. Air distribution,

air temperature and blower speed are controlled by the system. This system has “set and

forget” automatic functions which will maintain interior comfort regardless of ambient

temperatures.

• IHKA IV—same as IHKA except it has an integrated solar sensor and the REST button has

been replaced with a MAX button. The MAX button has two different functions: Maximum

Cooling and Residual Heat.

4.6.2 Important Tips for Testing Climate Control Systems

• The scan tool only communicates with IHKA systems (1997–2002 E39 and E46).

• Some of the IHKA inputs may communicate with other modules sent to the IHKA on the bus

communication line. Therefore, it may not always be possible to test an IHKA input directly.

Also keep in mind that the IHKA will display substituted scan tool values for faulty inputs,

which, except for the evaporator, are designed to keep the system operating.

• The IHKA On Board Self Diagnostic System stores up to seven codes. Not all faults set codes.

• Constant battery power supply (KL30) is necessary for IHKA operation as well as memory

(early systems). Before performing a battery parasitic draw test, allow the IHKA to power

down for 16 minutes to enter “sleep” mode. Switched ignition power (KL15) is required for

IHKA operation when the ignition is in the “run” position. This allows the system to operate

after the vehicle has been started (or limited IHKA operation if the engine is not running).

• In accordance with federal law, the electronic climate control system defaults to the defroster

mode of operation with the fan on LOW every time the vehicle is started or the ignition key

cycled. This ensures that the windshield will remain clear to prevent a safety hazard if the

Table 4-13 Climate control types and system description

Model Series Engine Series Year System

3 Series E46 1999–2003

IHKR

IHKA E46

5 Series E39 1997–2003

IHKR

IHKA E39

X5 E53 2000–03 IHKR, IHKA