Strategy for coordinating the operation of the injection system and air conditioning (Renault Espace III)

The injection system control unit and the air conditioning control unit are functionally connected to each other.

The "AC OUT" signal from the injection system control unit sends a signal to the air conditioning system control unit to permit or prohibit the start of the air conditioning compressor.

When the "AC ON" signal is received, the air conditioning control unit requests permission from the injection control unit to control the air conditioning compressor.

When the air conditioner is turned on, the engine idle speed increases from 800 min⁻¹ to a maximum of 875 min⁻¹.

In some engine operating modes, the injection system control unit prohibits the operation of the air conditioning compressor.

The operation of the air conditioning compressor is prohibited for 5 seconds when the engine is started.

If the accelerator pedal position changes significantly, when the engine speed is less than 3000 min⁻¹ and the vehicle speed is less than 110 km/h, the compressor is switched off for 5 seconds.

If the accelerator pedal potentiometer position is greater than 50%, the engine speed is less than 2250 min⁻¹ and the vehicle speed is less than 20 km/h, the compressor is switched off for 5 seconds.

If the position corresponding to the released accelerator pedal is not detected and the engine speed is less than 675 min⁻¹, the compressor is switched off. It is switched on after 5 seconds if the engine speed increases.

The air conditioning compressor does not turn on if the coolant temperature is more than 112°C.

The compressor is switched on after switching off at 110°C. The coolant temperature indicator lamp lights up at 120°C and goes out at 115°C.