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
33
This feature can be used when the vehicle is
traveling to check the A/C compressor pressure
values.
In test mode, 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 allows verification of the pump
when inside a garage. This is also useful when
working on the heating system to remove air
pockets trapped in the system.
When performing an A/C cooling test and having
the water pump shut off in switch/sensor test
mode is required, just set the passenger set
point temperature to the minimum 64°F (18°C)
to shut off the pump.
5.5 TEST MODE FOR ELECTRIC
MOTORS
The test mode allows testing the motors and
electric contactors without the need to have the
engine running.
Use this test mode for testing of the condenser
fans, evaporator fans, overhead compartment
fans, A/C compressor clutch activation, A/C
compressor unloader activation, driver’s unit hot
water solenoid valve and refrigerant solenoid
valve, passengers’ unit hot water solenoid valve
and refrigerant solenoid valve, water circulating
pump. Refer to Section 06: ELECTRICAL under
"TEST MODE FOR ELECTRICAL MOTORS" for
complete information.
5.6 MODES OF OPERATION
COOLING DEMAND
Conditions for engaging the
2
nd
speed on the evaporator
motor
- The 2
nd
speed engages if the passengers' area temperature is
1 degree above the set point and it reverts
to speed 1 if the
temperature gets equal or below the set point.
HEATING DEMAND
Conditions for hot water
circulating pump activation
- The pump turns ON if the outside temperature is equal or less
than 50°F (10°C), when heating is more likely to be needed
Note: To test pump operation, it is possible to keep it active
even if the outside temperature is above 50°F (10°C). See 5.2
ON DEMAND ACTIVATION OF HOT WATER CIRCULATING
PUMP.
The compressor unloader
operation is based on
pressure and on the
difference between the
passengers’ area
temperature and set point.
Right compressor cylinders
-
Stop if: The passengers’ area decreasing temperature
becomes less than 0.4°F above the set point (68°F) or if
compressor discharge pressure is above 290
psi, or if
compressor suction pressure is below 23 psi.
- Restart if: The Passengers’ area temperature is 1.3°F or more
above the set point and compressor discharge pressure is less
than 250 psi and compressor suction pressure is above 32 psi.
A/C compressor deactivation
pressure
- 310 psi
- In case of high pressure, the high pressure transducer
connected to the multiplex module deactivates the compressor
-
There is also a 350 psi pressure switch that acts to stop the
compressor in the instance that the multiplex module fails.
Compressor turns on
automatically if (2 required
conditions)
outside temperature is above 32°F
and
return air temperature in passengers’ area is 61°F or above
(∆T=7° with set point)

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