1--8
©
2012 Mobile Climate Control
T-348 Rev. 07/2012
open and close the damper to allow addition of fresh
air into the air entering the evaporator coil. For
additional information on air flow, refer to paragraph
1.9.
1.4.7 System Operating Controls And Components
The system is operated by a Mobile Climate Control
Micromax microprocessor controller which consist
of a relay board (Figure 1-11), logic board
(Figure 1-10), and manual operator switches. The
manual operating switches are located on the drivers
control and may consist of a single OEM supplied
ON/OFF switch, additional OEM supplied switches
or a Mobile Climate Control supplied Micromate
control panel (Figure 1-14). The logic board
regulates the operational cycles of the system by
energizing or de-energizing relays on the relay board
in response to deviations in interior temperature.
Modes of operation include Cooling, Heat and Vent.
On systems fitted with only an ON/OFF switch and
on systems with the Micromate set in the AUTO
mode, the logic board will cycle the system between
the operating modes as required to maintain desired
set point temperature.
In the vent mode the evaporator fans are operated to
circulate air in the bus interior.
In the heat mode the heat valve is opened to allow a
flow of engine coolant through the heat coils of the
evaporator coil. The evaporator fans operate to
circulate air over the evaporator coil in the same
manner as the vent mode.
In the cooling mode the compressor is energized
while the evaporator and condenser fans are
operated to provide refrigeration as required. The
compressor is fitted with cylinder unloaders to
match compressor capacity to the bus requirements.
Once interior temperature reaches the desired set
point, the system may operate in the clutch cycle or
reheat mode. A controller programmed for clutch
cycle will de-energize the compressor clutch and
allow the system to operate in the vent mode until
further
cooling
is
required.
A
controller
programmed for reheat will maintain compressor
operation and open the heat valve to allow reheating
of the return air. In the reheat mode interior
temperature is maintained at the desired set point
while additional dehumidification takes place.
Controls may also be provided to allow manual
operation of the evaporator fans in low or high speed
and manual control of the fresh air damper in the
open or closed position.
1.5 REFRIGERATION SYSTEM COMPONENT SPECIFI-
CATIONS
a. Refrigerant Charge
R-134a15.8 Lb (7.17 kg)
b. Compressor
UNIT MODEL
AC353
Compressor
05G
No of Cylinders
6
Weight - Dry
W/Clutch
145 lbs
(65.77 kg)
Oil Charge
5.5 pints
(2.6 liters)
Oil Level: Level in sight glass between Min.-Max marks on
compressor crankcase (curbside)
Approved Compressor Oils - R-134a:
Castrol: Icematic SW68C
Mobil: EAL Arctic 68
ICI: Emkarate RL68H
c. Thermostatic Expansion Valve:
Superheat Setting: 12
±
2
°
F (6.7
±
1
°
C)
d. High Pressure Switch (HPS):
Opens at: 350
±
10 psig (23.81
±
0.68bar)
Closes at: 250
±
10 psig (13.61
±
0.68bar)
e. Low Pressure Switch (LPS)
Opens at: 6
±
3psig (0.41
±
0.20 bar)
Closes at: 25
±
3 psig (1.7
±
0.20 bar)
f. Water Temperature Switch (WTS)
Bus manufacturer supplied - suggested close on tempera
ture rise at 105
°
F (41
°
C).
1.6 ELECTRICAL SPECIFICATIONS - MOTORS
a. Evaporator Fan Motor
Evaporator Motor
Brushless
Permanent
Magnet
24 VDC
Horsepower (kW)
0.53/0.39
0.4/0.3
Full Load Amps (FLA)
15.2
11.0
Operating Speed (RPM)
3830
3013
Bearing Lubrication
Factory Lubricated
(additional grease not required)
b. Condenser Fan Motor
Condenser Motor
Brushless
Permanent
Magnet
24 VDC
Horsepower (kW)
0.24/0.18
0.25/0.20
Full Load Amps (FLA)
7.0
7.2
Operating Speed (RPM)
2840
1900
Bearing Lubrication
Factory Lubricated
(additional grease not required)
