Compressor Control

Compressor Control


The control of the compressor is the same as that of the IHKS with the exception of the IHKA module signals compressor request to the EMS2000 via the K-bus and not the BC1. The evaporator sensor still signals to the BC1 as on the IHKS.


Compressor Cut-out Criteria
For both versions of air conditioning the following conditions will suspend the operation of the compressor:

- Full-load acceleration
- Engine coolant temperature > 118° C
- Engine speed > 6016 rpm.
- Engine speed < 500 rpm.
- Evaporator temperature < 2° C.
- Refrigerant pressure < 1.6 bar / > 30 bar.

Notes:

IHKA On Board Diagnosis
The on board diagnostics function is a special feature of the IHKA that provides three test modes:

- Mode 1 - Read fault memory
- Mode 2 - Calibration run
- Mode 3 - Manual check of functions

To access the on board diagnosis function the OFF button and the blower PLUS switch must be pressed simultaneously for approximately two seconds with the ignition in position 2. The central display panel will show a single "streamer bar" to represent mode 1 - Read fault memory. To access mode 1 the AUTO button must be pressed.

To select mode 2 or 3 it is necessary to press the OFF button, the second or third streamer bar illuminating will indicate the relevant mode to the Technician depending on how many times the OFF button is pressed. To access the mode the AUTO button must be pressed. To exit the on board diagnosis mode the ignition must be switched to the off position.

Mode 1: Read Fault Memory
The IHKA fault memory is read and displayed in the central display panel. If no faults are present 00 is displayed and if a fault is stored FF followed by a code number is displayed. This display flashes at 0.5 Hz.





Mode 2: Calibration Run
The objective of the calibration procedure is to correct the position drift of the servomotors for temperature and air distribution control. During a calibration run:

- Both servomotors are driven to their two end positions and the new values stored in the IHKA EEPROM.
- All LED's activated simultaneously.
- Blower streamer bars individually illuminated.
- CA flashes in the central display panel at 0.5 Hz.

There are three possible operating statuses shown in the central display:

- CA = Calibration Active
- CC = Calibration Complete
- FF = Fault

Mode 3: Manual Mode
In this mode blower, air distribution, recirculation, heated screens, air conditioning ON/OFF and temperature are manually controlled.

If the engine is running, and the blower is operational, the air conditioning will be controlled manually by the AC switch. The AUTO, OFF or programmed defrost functions will not be allowed in this mode.