Citroen C5 Aircross Quiz
Air conditioning

Heater resistors

In this manual: Air conditioning
AAS - Parking Aid — 8Owner's Manual Citroën C5 II — 139Citroen C5 Aircross (2017- 2024) - Owner's Manual — 143Audio system — 14Overspeed control — 7Multifunction display — 4Driver information instrument cluster — 20Navigation assistance — 8Intruder alarm — 7Mechanical specifications — 9Power supply — 8Electrical equipment — 13Lighting and electrical equipment — 3Immobiliser — 4Sunroof — 10Exterior lighting / signalling — 38Multiplexing — 7Air conditioning — 7Body — 6General specifications — 9Automatic gearbox control — 3Exterior mirrors — 10Airbags — 5Defrost — 6Underinflation — 6Interior lighting — 4Wipers / Washers — 6Window lifters — 11Cooling — 8Opening management — 7Cruise control — 5Suspension — 4Grip management — 1Paint — 2Exterior lighting control — 1Indicators (turn signals) — 1Automatic lighting systems - General recommendations — 1Wiper control — 1Special position of the front wipers — 1
~2min read

Performance

The heater resistors are intended to improve the warm-up of the vehicle cabin.

Heating is provided by 3 air heater resistors (R1, R2 and R3), located in the heating and air conditioning unit.

Wiring diagram

Resistances de rechauffage schéma structurel
Heater resistors wiring diagram

Key:

  • CA1: 300 W power control
  • CA2: 600 W power control
  • R1: 1st heater resistor (power = 300 W)
  • R2: 2nd heater resistor (power = 300 W)
  • R3: 3rd heater resistor (power = 300 W)

Functional description

The auxiliary heating request is managed by the BSI.

The heater resistors are controlled by the engine ECU.

The BSI generates the auxiliary heating request based on the following information:

  • Engine coolant temperature,
  • Outside temperature (from the passenger-side mirror sensor).

The heater resistor power request is shown by the following curve:

La demande de d'alimentation des résistances

Heater resistor power request

Key:

  • Solid line: heater switch-off threshold
  • Dash-dot line: heater switch-on threshold
  • A: Heater activation request range
  • B: Heater deactivation request range
  • Te: Outside temperature
  • Tm: Engine coolant temperature

The BSI then sends the request to the engine ECU via the CAN network, according to the table below:

Temporisation d'allumage / coupure des résistances de réchauffage

Switch-on / switch-off delay of heater resistors

To preserve engine performance and avoid overloading the electrical system, the heater resistors are switched on and off in 20-second steps.

Note: The engine running signal is required to switch on the heater resistors.

Switching off the engine immediately cuts outputs CA1 and CA2.

Switching on the heater resistors

Note: When the engine running signal appears, the BSI starts a 60-second stabilisation delay before the heater resistors are switched on.

Cas de la coupure des résistances

Switching off the heater resistors

Modes dégradés

Degraded modes

The degraded modes for the resistor auxiliary heating are as follows:

  • Outside temperature information invalid: switching on the heater resistors is prohibited,
  • Engine coolant temperature information invalid: switching on the heater resistors is prohibited.

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