A/C Compressor Control

Evaporator control

Evaporator control is activated by pressing the KLIMA button in the operating unit. The A/C standby is indicates by the LED in the KLIMA button. If controlled compressors are installed, the cutout threshold is dependent on the outside temperature and may be between 34�F and 37�F (1�C and 3�C). If a standard compressor is installed, the threshold is reduced by 34�F (1�C) at high outside temperatures (> 86�F/30�C). The compressor and auxiliary fan are controlled directly by the DME via the air-conditioning compressor relay.

Requests for A/C compressor and auxiliary fan are sent to the DME via the Requests for A/C compressor and auxiliary fan are sent to the DME via the K-bus. The request air conditioner ON comes from the IHKA and from the ZKE in the case of IHKR.

The DME receives the instruction to switch on the compressor via the K-bus . Provided full load cutout is not active, the DME switches on the compressor via a relay.

Switching conditions for the magnetic clutch:

ON: A/C button ON and evaporator temperature > 39�F (4�C) (depending on the outside temperature) and coolant temperature < 243�F (117�C) and terminal 30 at control module > 9.7 volts.

OFF: A/C button OFF or evaporator temperature < 37�F (3�C) (depending on outside temperature) or blower stage 0 or coolant temperature > 248�F (120�C) or terminal 15 OFF or terminal 30 < 9 volts.

The pressure sensor is a sensor of the DME. It switches off the compressor if the pressure is too low or too high. The evaporator sensor is a sensor of the central body electrical system.

Auxiliary fan control:

The pressure sensor is used to record the refrigerant pressure of the air conditioning system. From this, the DME generates stage I or II for the fan motor.