OPERATION
The FFBH system operates in two modes
- Parked heating, to heat the passenger compartment while the vehicle is parked with the engine off.
- Additional heating, to boost heater performance while the engine is running.
The automatic temperature control (ATC) module disables FFBH operation if battery voltage is too low, as determined from an ambient air temperature dependent voltage map. Where fitted, the battery monitoring system can also disable FFBH operation based on the battery charge state with the engine off.
During FFBH operation, with or without the engine running, the coolant valves of the climate control system remain de-energized and heater core temperature is directly related to the temperature of the coolant coming from the FFBH unit.