PREVOST LE MIRAGE XLII BUS SHELLS User Manual

Section 22: HEATING AND AIR CONDITIONING
PA1553
13
Problem/Symptom Probable Causes Actions
2. Check / reset circuit breaker CB7
3. Check / replace fuse F12
The A/C compressor clutch
does not engage
Module A52 is not powered or is
faulty
1. Check the SYSTEM DIAGNOSTIC menu
of the message center display (MCD).
Select FAULT DIAGNOSTIC and
ELECTRICAL SYSTEM. The message
“Voltage Module A52, Value too Low,
Active” confirms a power problem on the
module
2. Check / reset circuit breaker CB7
3. Check / replace fuse F65
Evaporator fan not
functioning
Circuit breaker CB4 tripped
Module A54 is not powered or is
faulty
Faulty brushes
1. Check / reset circuit breaker CB4
2. Check the SYSTEM DIAGNOSTIC menu
of the message center display (MCD).
Select FAULT DIAGNOSTIC and
ELECTRICAL SYSTEM. The message
“Voltage Module A54, Value too Low,
Active” confirms a power problem on the
module
3. Check / reset circuit breaker CB4
4. Check / replace fuse F67 , F68
8. CENTRAL HVAC SYSTEM - AIR
CONDITIONING
The schematic of Figure 16 shows the central A/C
system and its components. The central system is
equipped with a 6 cylinder, 05G-134A Carrier
compressor with an air conditioning capacity of
7½ tons. The receiver tank and filter dryer are
mounted inside the condenser compartment.
XLII Converted vehicles may be supplied with a
central or small A/C system (Fig. 16 and 40). For
vehicles equipped with a small A/C system, refer
to paragraph 10: SMALL HVAC SYSTEM – AIR
CONDITIONING COMPONENTS further in this
section.
8.1 A/C CYCLE
Refrigeration may be defined as "the transfer of
heat from a place where it is not wanted to a
place where it is unobjectionable". Components
required for a closed circuit refrigeration system
are shown in Figures 16 and 41.
The air conditioning system used on XLII series
vehicle is of the "Closed" type using "R-134a".
1. The refrigerant flowing to the compressor is
compressed to high pressure and reaches a
temperature higher than the surrounding
air. It is passed through the air-cooled fins
and tubes of the condenser causing the hot,
high pressure gas to be condensed into a
liquid form.
2. The liquid refrigerant flows to the receiver
tank, then back to the condenser sub-
cooler. It leaves the condenser and passes
through a filter dryer where moisture, acids
and dirt are removed and then through a
moisture indicator which indicates if any
moisture is present in the system.
3. By its own pressure, the liquid refrigerant
flows through a thermal expansion valve
where the pressure drop causes the
refrigerant to vaporize in a vapor-liquid state
at a low temperature pressure.
4. The cold low pressure refrigerant passes
through the main and the driver’s
evaporator coils which absorbs heat from
the air passing over the fins and tubes, and
changes into gas. In this form, the
refrigerant is drawn into the compressor to
repeat the air conditioning cycle.

PREVOST LE MIRAGE XLII BUS SHELLS Specifications

General

Brand	PREVOST
Model	LE MIRAGE XLII BUS SHELLS
Category	Buses
Language	English