PREVOST H3-41 Maintenance Manual

SECTION 22: HEATING AND AIR CONDITIONING
PA1621 Maintenance Manual All Series | Section Revised November 2017
55
Draining Passenger’s Unit Heater Core
1. Stop engine and allow engine coolant to cool.
2. Close both heater line shutoff valves (Figure
72 or Figure 73). 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.
FIGURE 73: H3 SERIES HEATER LINE SHUTOFF
VALVES
05144
WARNING
Before proceeding with the following step,
check that coolant has cooled down.
4. Open drain cock in bottom of heater core
(Figure 74) 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 74: HEATER CORE DRAIN COCK LOCATION
6.4.4 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
6.4.5 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 heating system.

PREVOST H3-41 Specifications

General

Brand	PREVOST
Model	H3-41
Category	Motorhomes
Language	English