Description And Operation
The climate of the vehicle through the heater assembly can be insufficient due to a cold engine. An additional system of heating is in place that is activated in the first instants of operation of the engine, according to the temperature reached by the engine coolant.
The system consists of a device for additional heating, located inside the heater assembly: in this device are located two resistors (PTC1 - 250W, and PTC2 - 500W).
The operation of the resistors is controlled by the A/C heater control which activates one or two, thus providing a progressive heating with a maximum power of 750 W, determined by a control logic that depends on:
- The outside temperature below 20°C (68°F)
- The temperature reached by the coolant of the engine about 70°C (158°F)
- The number of revolutions of the engine (which must be greater than 700 rpm)
- The battery voltage (which must not fall below 12.6 V)
The power of one or two resistors is controlled through two relays placed on the HVAC housing:
- Level 1: activation of the first relay (250W)
- Level 2: activation of the second relay (500W)
- Level 3: activation of both relays (750W)
The supply line is protected by two "MAXIFUSE", contained in the box on the positive battery terminal.
The PTC heater unit is accessed for service without removing the instrument panel.