Valeooscope - Air Conditioning System Thermal comfort loop

9. The Heating Ventilation and Air Conditioning unit (HVAC)

9.9 Hot/cold mix

9.9.2 By adjusting the hot water flow

The control of the hot/cold mix depends on the system architecture. In most cases the HVAC is designed with an air mixing solution, but the temperature can also be controlled by the water flow rate in the heater core. 9.9.1 By air mixing In manual air conditioning systems, the air is mixed using flaps inside the HVAC. The flaps are actuated from the control panel using cables. Automatic air conditioning systems apply the same principle, but they are fitted with motor-driven mixing flaps. The mix of hot and cold air is permanently adjusted in order to regulate the temperature in the cabin to the set point.

Some systems can adjust the hot temperature by acting on the flow rate of hot water in the heating radiator. This variant exists in both manual and automatic air conditioning systems and uses either a mecha- nical valve controlled by a cable, or electrovalves controlled by the air conditioning ECU .

Heat control in the heater core

Flow control via a mechanical tap

inlet

Mechanical control panel (via a bowden cable)

Flow control via an electro-actuator

A/C control unit (PWM controlled)

inlet

The mixing function is located inside the HVAC at the junction of hot and cold air streams

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