MCi Crusader II 1989 Maintenance Manual page 126

Date 1-1-89
Page· __
3_-s_1 _ _
MC-9 MAINTENANCE MANUAL
TROUBLESHOOTING
There are basic steps in troubleshooting the dual-voltage
refrigerator that, iffotlowed. make problem pinpointing a simple
process. The three major component assemblies that will pre-
vent operation are:
1. Compressor and System Assembly
This assembly consists of the swing motor compressor,
condenser, dryer, capillary tube, and evaporator plate. After
these components have been connected to form a closed loop
or circulator system, this system is then charged with a
measured amount of refrigerating gas Dichlorodifluoromethane
R-12 and sealed to fom, a noncontaminated, closed system
through which the gas is recycled over and over again during
the refrigeration process.
Should a leak occur at any time in this system which allows
this gas to escape, then the refrigeration capabilities of the
system are terminated. A common symptom that the system has
a leak is that the compressor runs continuously, but no cooling
is obtained.
2. The Oscillator Transfonner Assembly
This assembly consists of a dual-voltage transformer and a
solid-state oscillator. The oscillator is in operation on DC only
and its only function is to invert the 12-volt DC power supply to
110 volts AC. The dual-voltage transformer ensures that the
correct AC voltage (20V AC) is supplied to the swing motor
compressor.
3. The Thermostat
This item is an adjustable temperature cold control that
senses the temperature within the refrigerator and maintains it
at the desired setting. Should this control fail. it may produce
two different reactions: (a) The refrigerator will not operate and
the unit will begin defrosting, or (b) the unit will not cycle but
will run continuously, with the result that refrigeration temper-
atures are extremely cold in some cases. causing foodstuffs
such as milk, soft drinks, or other liquids to freeze.
Troubleshooting your refrigerator becomes much easier if
the conditions of operation with relation to the malfunction are
known. An inoperative unit, dependent upon what component
has caused the malfunction, has certain symptoms that, if
known, will facilitate repairs. These symptoms are:
1. Insufficient Cooling
(compressor does not run)
Gas leak or defective contacts at thermostat
Short circuit in motor, blown fuse, broken power supply
cord or faulty transformer connections
Transformer burned out
Incorrect voltage supply
2. Insufficient Cooling
(compressor runs)
Refrigerant leak
System freeze-up, clogging or uneven distribution of
compressor oil (shut off until cool, run for 5 minutes, shut
off, run for 5 minutes, and repeat).
Dirty condensor
Insufficient cooling air to condensor
3. Refrigerator Too Cold
Thermostat incorrectly set, points worn, shorted or
grounded out
Loose thermostat capillary tube
4. Abnormal Loud Noise
Loose parts in machine compartment
Compressor mounting springs touching
5. Compressor Does Not Operate On Both AC And DC
Polarity reversed
Weak battery
Faulty thermostat
Oscillator defective
Faulty transformer
6. Intermittent Running
Oscillator transistors shorted ·
7. Excess Frost Build~Up
Too much food stored blocking cooling air movement
Defrost refrigerator