Auxiliary Heating: Overview Land Rover Range Rover III facelift

OVERVIEW

The system consists of a FFBH unit and a FFBH fuel pump. On vehicles with the remote operation feature, the system also includes a changeover valve, a FFBH receiver and a remote handset.

Fuel for the FFBH system is taken from the vehicle fuel tank, through a line attached to the fuel tank top flange assembly, and supplied via the FFBH fuel pump to the FFBH unit. In the FFBH unit, the fuel delivered by the FFBH fuel pump is burned and the resultant heat output is used to heat the engine coolant.

Where fitted, the changeover valve allows the heater coolant circuit to be isolated from the engine coolant circuit during parked heating.

A control module integrated into the FFBH unit controls the operation of the FFBH unit and the FFBH fuel pump. The automatic temperature control (ATC) module controls the changeover valve. System operation is initiated by

1. The instrument cluster, via the automatic temperature control (ATC) module, for parked heating selections made on the Touch Screen Display (TSD). Refer to «Audio System»(ref-522679-S21769648732013011500000) .
2. The remote handset, via the Television (TV) system antenna and antenna amplifier, and the FFBH receiver, for remote activation of parked heating.
3. The automatic temperature control (ATC) module, for additional heating while the engine is running.

PRINCIPLES OF OPERATION

The FFBH system operates in two modes

1. Parked heating, to heat the passenger compartment while the vehicle is parked with the engine off.
2. 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

1. When the engine is off the low voltage limit is 11.4 V for more than 10 seconds; the system is re-enabled if battery voltage increases to 12.2 V.
2. When the engine is running the low voltage limit varies with ambient temperature, from 11.1 V at -25°C (-13°F) and below to 11.7 V at 15 °C (59 °F) and above; if battery voltage is below the limit for 2 minutes the system is disabled for the remainder of the ignition cycle.

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.