Cabin Heater

Vehicles equipped with the optional diesel engine are also equipped with a supplemental heater unit. This unit is mounted under the vehicle and operates similar to an oil fired furnace. The heater burns small amounts of fuel to provide additional heat to the coolant. Coolant is routed from the engine, to the supplemental heater, and then to the front heater core. This provides additional heat to the passenger compartment. The system is interfaced to the vehicles on-board computer systems and DRBIII(R) diagnostics.

The supplemental heater unit has an electronic control module that monitors the heat output of the heater. The heater operates at full load (5 kW), half load or idle mode (no additional heat) depending on coolant temperature.

The supplemental heater is activated via the temperature control on the heater-A/C control. The heater is activated when the temperature control is set to/or above the upper set point. The supplemental heater can operate in a full or partial load range as well as an idle mode, all dependent on the engine coolant temperature. The heater unit will also turn off if the temperature control is set to less than the lower set point. The supplemental heater can take up to three minutes to completely shut down when either the heater temperature is set below the lower set point or the vehicle ignition is turned off.

The supplemental heater only operates when the engine is running, the mileage exceeds 8 kilometer (5 mph) and the fuel tank volume exceeds 1/8 of a tank. The heater should start if the coolant temperature is below 40° C (104° F).

NOTE: Do not apply a strong vacuum directly on the supplemental heater exhaust line. Place the vacuum within 75 mm (3 inches) of the exhaust port. Too strong of a vacuum can prevent the heater from starting. The heater control module monitors the supplemental blower speed and combustion during its start-up.