MCC 68AC430-100, Operation & Service Manual

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1--3
©
2012 Mobile Climate Control T-353 Rev. 01/2013
1.2.4 BT-324 Microprocessor
This BT-324 controller has three (3) modes, Auto,
Vent (Cycle clutch type) and Heat.
In the auto mode the compressor is energized while
the evaporator and condenser fans are operated to
provide refrigeration as required. The compressor (s)
capacity is matched to the bus requirements. Once
interior temperature reaches the desired set point,
the compressor(s) is de-energized.
In the heat mode the heat valves are opened to allow
a flow of engine coolant through the heat coils
located in the evaporator section. The evaporator
fans operate to circulate air over the heat coils in the
same manner as the cooling mode.
1.3 REFRIGERATION SYSTEM COMPONENT SPECIFI-
CATIONS
a. Refrigerant Charge R-134a (Approximate)
NOTE
Refrigerant charge will depend on hose
lengths and diameters; or if there is an In-
Dash unit (front evaporator). The following
should only be used as a guideline.
AC430 Single Loop TM-21 Compressor
11 Pounds (5 kg)
b.
Compressors
Compressor TM-21
Weight, (Dry) 7.5 Lbs. (3.4 kg)
Oil Charge
6.1 Oz. (180 cc) PAG
c. Thermostatic Expansion Valves:
TDEN 5.8 TR
Superheat Setting Factory Set at 12
°
F ( ± 1.8
°
F)
6.7°C ( ± 1 ° C)
TGEN 4.5
Superheat Setting Factory Set at 7.2
°
F ( 4°C )
MOP 70 psig ( 4.8 bar )
d. High Pressure Switch (HPS)
Normally Closed
Opens at: 360
±
10 psig (20.41
±
0.68bar)
Closes at: 280 ± 10 psig (13.61 ± 0.68bar)
e. Low Pressure Switch (LPS)
Normally Open
Opens at: 6 ± 3psig (0.41 ± 0.20 bar)
Closes at: 25 ± 3 psig (1.7 ± 0.20 bar)
1.4 ELECTRICAL SPECIFICATIONS - MOTORS
a. Evaporator Blower/Motor
Evaporator Motor
Brushless
12 VDC
Horsepower (kW) .375 (.28)
Full Load Amps (FLA) 20.7
Operating Speed
High(RPM)
3250
Bearing Lubrication
Factory Lubricated
(additional grease not required)
b. Condenser Fan Motor
Condenser Motor
Permanent Magnet
12 VDC
Horsepower (kW) 1/4 (.18)
Full Load Amps (FLA) @
13.5 VDC
14.4
Operating Speed
High(RPM)
3222
Bearing Lubrication
Factory Lubricated
(additional grease not required)
c. Return Air Sensor
Input Range: -40 to 176
°
F (-40 to 80
°
C )
Output: 20K ohms at 77 ° F (25 ° C )
d. Ambient Sensor (location chosen by Installer)
Input Range: -40 to 302
°
F (-40 to 150
°
C )
Output: 20K ohms at 77 ° F (25 ° C )
Opens at: 25 ° F (10 ° C )
Closes at: 35
°
F (1.7
°
C )
1.5 SAFETY DEVICES
System components are protected from damage
caused by unsafe operating conditions with safety
devices. Safety devices with Mobile Climate Control
supplied equipment include high pressure switch
(HPS), low pressure switch (LPS), circuit breakers
and fuses.
a. Pressure Switches
High Pressure Switch (HPS)
During the air conditioning cycle, compressor clutch
operation will automatically stop if the HPS switch
contacts open due to an unsafe operating condition.
Opening HPS contacts de-energizes the compressor
clutch shutting down the compressor. The high
pressure switch (HPS) is installed in the condenser
section.