PREVOST X3-45 COMMUTER User Manual

SECTION 22: HEATING AND AIR CONDITIONING
DOB 1300-1556 | X3-45 Commuter PA-1648 Maintenance Manual First release Oct 2020
47
Draining Passenger’s Unit Heater Core
1. Stop engine and allow the engine coolant to
cool.
2. Close both heater line shutoff valves (Figure
54). One is located in the engine
compartment, lower road side, near the
radiator while the other one is located behind
the L.H. hinged rear fender near the
preheater.
3. Open the evaporator compartment door.
WARNING
Before proceeding with the following step,
check that coolant has cooled down.
4. Open drain cock in bottom of heater core
(Figure 55) you can unfasten a hose
connection on top of heater core in order to
allow air to enter while draining. The main
heater core drain cock is located in the
evaporator compartment. To access the
valve, open baggage compartment door
located in front of the evaporator
compartment (L.H. side). Open the
evaporator compartment access panel.
FIGURE 55: HEATER CORE DRAIN COCK LOCATION
6.6.4 Filling Heating System
1. Ensure that the driver’s unit heater core
purge valve and the passenger’s unit heater
core drain cock are closed.
2. Open the surge tank filler cap and slowly fill
the tank to top of sight glass.
3. After initial filling, the hot water shutoff
valves should be open and the water
circulating pump should be energized to
assist in circulating coolant through the
heating system. To perform this operation,
start the engine, switch on the HVAC
control unit, both driver and passenger
sections, and set temperature to their
maximum positions in order to request the
heating mode in each of these sections.
4. When coolant level drops below the surge
tank sight glass, slowly fill the tank to top of
the sight glass.
5. If vehicle is equipped with a windshield
upper section defroster, open front baggage
compartment R.H. side door. Locate
circulating pump on top of front
wheelhousing, momentarily pinch the hose
located between the circulating pump
suction and the defroster outlet connector to
ensure windshield upper section defroster
complete filling.
6. Once the level has been stabilized, replace
cap
6.6.5 Bleeding Heating System
Whenever the heating system has been drained
and refilled, or the system has run low on
coolant and coolant has been added, it is
necessary to bleed air from the heating system.
Locate the purge valve illustrated in Figure 51 &
Figure 55, and open them momentarily until no
air escapes from the lines. If present, open the
manual vent located inside the HVAC unit, on
the driver’s side.
NOTE
In test mode (see paragraph 5.4 TEST MODE
FOR SWITCHES AND SENSORS
), with the
parking brake applied and the passenger set
point set to a value higher than 64°F (18°C),
the hot water circulating pump is not set to
OFF as it would normally do when the outside
temperature gets above 50°F (10°C). This
feature is useful when working on the heating
system to remove air pockets trapped in the
system.
6.7 COOLING
The central system is equipped with 4-cylinder
4NFCY Bitzer compressor with an air

PREVOST X3-45 COMMUTER Specifications

General

Engine	Volvo D13
Transmission	Allison B500
Fuel Type	Diesel
Length	45 ft (13.7 m)
Width	102 in (2.6 m)
Horsepower	500 hp
GVWR	54, 000 lbs
Height	141 in