Load & Lock; Preheater; Switching The Heater On - PREVOST H3-45 2023 Operator's Manual

5-16 Other Features
2. The steering wheel's rotation becomes less
than 3/4 turn.
LOAD & LOCK
This mode locks the tag axle in loaded state,
preventing any automatic control activation for a
brief period. When selected by the driver by
pressing and holding the switch down for 3
seconds, the air pressure will be maintained even
if the conditions for unloading are met. This is
useful for keeping the ride height and preventing
potential rubbing of the rear bumper on the
ground in certain situations.
This self- canceling mode reverts to Automatic
Mode after a delay of 10 seconds or once the
vehicle speed exceeds 20 mph (32 km/h) for
more than 6 seconds.
FIGURE 5: SYSTEM STATUS PICTOGRAM - TAG AXLE
LOADED & LOCKED
CAUTION
Do not leave the tag axle in unloaded position
for an extended period. Unloading the tag axle
increases load on the drive axle, suspension
and tires.
Avoid driving vehicle with tag axle unloaded
when speed exceeds 12 mph (20 km/h).
In order to prevent damage to the suspension,
always unload the tag axle before lifting the
vehicle for servicing.

PREHEATER

The optional auxiliary heating system is used for
preheating and retaining the heat of water-cooled
engines. It can be used before start-up to ease
starting and to provide rapid interior heat. It can
also be used with the engine running to maintain
coolant heat and interior temperature.
The heater operates independently of the engine.
It is connected to the cooling system heating
circuits and to the vehicle's fuel and electrical
system.
The preheater uses the same fuel as the engine.
Do not operate in a closed building or while
refueling. Operate only in a well-ventilated area.

SWITCHING THE HEATER ON

The Heater "On"
display when the heater is switched on. Air is
forced in to flush out the combustion chamber of
any residual gases and the water circulation
pump begins operating. The fuel metering pump
delivers fuel to the combustion chamber, where
fuel and combustion air form a combustible
mixture which is ignited by the ignition unit.
Once the flame sensor has signaled to the control
unit that combustion has taken place, the ignition
unit is switched off.
Hot combustion gases are diverted at the end of
the flame pipe and are then forced through the
indirect heating surfaces of the heat exchanger.
The heat exchanger transfers the heat to the
coolant
exchanger.
FIGURE 6: COOLANT PREHEATER
The heater is thermostatically controlled and
operates intermittently (i.e., the switched-on time
of the burner varies depending on the heat
requirement).
controlled by the built-in water thermostat.
The water circulation pump remains in operation
as long as the heater is operating, even during
the regulated intervals and during the delayed
cut- out of the heater. The pump can also be
PA-1652 Operator's Manual H3-45 Coach
WARNING
symbol appears on the timer
water passing through
The water temperature
the heat
is