Norcold DC-0040 User manual

Refrigerator
Service Manual
Models:
DC0040(K), DC0051(K)
DE0040, DE0051
DE0240T, DE0251T
Norcold, Inc.
P.O. Box 4248
Sidney, OH 45365-4248
Part No.623011A(08/03)

Troubleshooting – Table of Contents
Ø Procedure A – Thermostat “ON” compressor does not run… 3
Ø Procedure B – Compressor resistance……………………….. 4
Ø Procedure C – Power supply output voltage…………………. 5
Ø Procedure D – Compressor amp draw…………………………6
Ø Procedure E – Evaporator thermistor resistance…………….. 7
Ø Procedure F – Insufficient cooling………………………………8
Ø Procedure G – Refrigerator too cold……………………………8
Ø Procedure H – Auto shut-off device…………………………….8
Ø Procedure I – Ventilation…………………………………………9
Ø Wiring schematic………………………………………………….9
Ø Quick reference repair sheet…………………………………….10
Warning
!
Perform all tests using a fully charged 12V DC battery.
Using other equipment that supplies DC voltage may
cause permanent refrigerator component failure.
2

Troubleshooting – Procedure A
Thermostat “ON” Compressor Does Not Run
Measure Terminal
Voltage Of Temperature
Control Between TP1 &
TP2. (See Figure 1)
DC 0V
DC 5V
DC 2V
Short Circuit
Normal
DC Power
Supply Failure Change DC Power Supply
Change DC
Power Supply
See
Procedure B
Measure Terminal
Voltage of Temperature
Control Between TP2 &
TP3. (See Figure 1)
Is Temperature
Control LED on? YES
NO
Correct
Voltage OK
Check Supply
Voltage
(10.5 – 32V DC)
(85 – 132V AC)
CORRECT
INCORRECT Compressor
Runs YES
NO
Replace
10A Fuse
(See Figure 2)
Reverse Polarity
& Check Operation
(Red + / Black -) OK
Replace
10A Fuse
(See Figure 2) OK
Check DC
Polarity INCORRECT
OK
Compressor
Runs YES
NO
Check Both
DC Fuses BLOWN
OK
Compressor
Runs YES
NO
DC 0V
DC 12
to 32V
DC Power
Supply Failure
Normal
Change DC
Power Supply
See
Procedure B
Note: Measurements taken with 12.8V DC or 120V AC power supply.
Check AC
Power Supply
(37 – 45V DC)
(See Figure 5)
Change AC
Power Supply
Short Circuit Change DC
Power Supply
GOOD
BAD
AC
OPERATION
DC
OPERATION
Power
Source DC
AC
Check AC
Power Supply
(37 – 45V DC)
(See Figure 5)
DC Power
Supply Failure Change DC Power Supply
Change AC
Power Supply
GOOD
BAD
DC
OPERATION
AC
OPERATION
3
Red
TP3
TP1
TP2
Figure 1 – Temperature Control
Brown Black
Figure 2 – Fuse Locations
Note: If 10 Amp fuse is blown,
check wiring of vehicle.

Troubleshooting – Procedure B
Compressor Resistance
Measure
Compressor
Resistance
(See Figure 3)
0 W
¥ W
1.4 – 3.5 WNormal
Internal
Compressor
Failure
See
Procedure C
Change
Cooling Unit
Note: Perform procedure at room temperature.
Figure 3 – Measuring Compressor
Resistance
A
B
Turn the refrigerator to OFF.
Remove the black wire to the compressor. Measure the
resistance of the compressor between point A and point B.
4

Troubleshooting – Procedure C
Power Supply Output Voltage
Measure Voltage
BetweenA & B
At the Compressor
(See Figure 4)
Less than
15V AC
0V AC
15 –25V
AC
DC Power
Supply Failure
DC Power
Supply Failure
Normal
Go to
Procedure E
Change DC
Power Supply
Change DC
Power Supply
Change
Thermistor
FAULTY
THERMISTOR
GOOD
THERMISTOR
See
Procedure D
Note: Measurements taken with 12.8V DC or 120V AC power supply.
DC
OPERATION Check AC Power
Supply.
(37 – 45V DC)
(See Figure 5)
AC
OPERATION DC Power
Supply Failure Change DC Power Supply
Change AC
Power Supply
Power
Source
Check AC Power
Supply.
(37 – 45V DC)
(See Figure 5)
DC Power
Supply Failure Change DC Power Supply
Change AC
Power Supply
GOOD
BAD
DC
AC
GOOD
BAD
Figure 5 – Measuring AC Power
Supply Output
B
A
Figure 4 – Measuring Power
Supply Output Voltage
5

Troubleshooting – Procedure D
Compressor Amp Draw
Measure Amperage at
‘A’ on the Compressor
(See Figure 6) Normal
40Watt = 1.6 - 2.0Amps
60Watt = 2.7 - 3.3Amps
40Watt < 1.6Amps
60Watt < 2.7Amps
40Watt > 2.0Amps
60Watt > 3.3Amps
Compressor
Failure
Compressor
Failure
Change
Cooling Unit
Change
Cooling Unit
Note: Measurements taken with 12.8V DC power supply.
Compressor
A
Figure 6 – Measuring Amp Draw
of Compressor
6

Troubleshooting – Procedure E
Thermistor Operation Verification
To measure the resistance of the
evaporator thermistor, turn the
refrigerator to the OFF position.
Disconnect the three-pole connector
(Figure 7), and measure resistance
across the two pins. (Figure 8)
Check the evaporator thermistor by
measuring the temperature and
resistance of the thermistor. Refer to
Table 1 for a listing of acceptable
resistance ranges.
In general:
1.6K – 29KW= good thermistor.
¥W = defective thermistor. An open
thermistor will stop normal compressor
operation. Replace the defective
thermistor.
Evaporator Thermistor Resistance
Thermistor Temperature
( °F ) ( °C ) Resistance Allowable
Resistance Range
0 -18
9.7 KW8.7 - 10.7 KW
10 -12
7.8 KW7.0 – 8.6 KW
20 -7
6.4 KW5.7 – 7.0 KW
30 -1
5.3 KW4.8 – 5.7 KW
40 4
4.5 KW4.0 – 4.9 KW
50 10
3.6 KW3.2 – 4.0 KW
60 16
2.8 KW2.5 – 3.1 KW
70 21
2.1 KW1.9 – 2.3 KW
80 27
1.9 KW1.7 – 2.0 KW
90 32
1.8 KW1.6 – 1.9 KW
(Table 1)
Figure 8 – Measure Resistance
A
cross Pins
Figure 7 – Evaporator Thermistor
Connection (inside power supply)
7

Troubleshooting – Procedure F
Insufficient Cooling
Note: Check input voltage before
proceeding. Refer to Procedure A.
If compressor runs continuously:
Ø Check the voltage across the fan
leads. There will be a slight
voltage reading even if the fan isn’t
operational. The fan will only
operate when the compressor is
running, and the ambient
temperature is sufficient to engage
the fan. The operational voltage of
the fan is between 17 and 22VDC.
If this is present at the leads and
the fan is not running, replace the
fan. (Note: When servicing fan,
do not short the wires; this will
damage the power supply.
Ø Make sure the ventilation vents are
not blocked. Refer to Procedure I.
Ø Make sure the auto shut-off device
is operational. Refer to Procedure
H.
Ø If the reason for insufficient cooling
is not found, start with Procedure
B.
Replace cooling unit if:
Ø Compressor is hot to the touch and
not vibrating.
Ø Compressor vibrates and no
cooling
Troubleshooting – Procedure G
Refrigerator too Cold
Ø Adjust temperature control to lower setting. (#1 = Warm, #5 = Coldest.)
Ø Make sure thermistor is securely mounted to the evaporator plate.
Ø If the reason is not found, refer to Procedure E.
Troubleshooting – Procedure H
Auto Shut-off Device
Note: Only the 12/24V DC models are
equipped with the auto shut-off device
within the power supply.
Shut-off Device Operation
To protect the cooling unit from
overheating, the refrigerator will
automatically shut-off when the ambient
air temperature is approximately 110°F. If
shut-off occurs, the refrigerator will sound
an intermittent alarm tone. To stop the
alarm, the refrigerator must be restarted.
This can be done by turning the
thermostat knob counterclockwise to the
OFF position and then turning it back to
the desired setting. The refrigerator will
not restart until the ambient conditions
allow for normal operation. The
functionality of the shut-off device can be
tested by heating it with a heat gun (See
Figure 9).
TH2
Figure 9 – High Temperature
Shut-off Device
8

Ventilation – Procedure I
Ventilation is necessary for the correct
operation of the refrigerator. Good
ventilation also increases the life of the
refrigerator cooling system. The current
models are equipped with built-in
ventilation systems that draw cooler air
through the lower intake vent. This air is
then circulated over the cooling unit to
remove excess heat from the cooling
system. The heated air is then rejected
through the upper vent. If this airflow is
blocked or decreased, the refrigerator
will not cool correctly. Do not block the
vents by closet or cabinet doors. Vent
blockage that reduces the vent area can
cause:
Ø Shortened life of the refrigeration-
cooling unit.
Ø Poor cooling performance of the
refrigerator.
Ø Continuous operation of the
refrigerator.
Ø Fast battery discharge.
Ø Void the refrigerator warranty.
Troubleshooting – Wiring Schematic
~
+
AC 85~132V
ORANGE
WHITE
AC IN(L)
AC IN(N)
B3P-VH AC/DC
converter
AC/DC PART
+
-
DC OUT + RED
DC OUT - BLACK
DC INPUT
CN1
B2P-VH
FAN MOTOR
24V DC
RED BLACK
XHP-2
B2B-XH-A
CONDENSOR
COUPLING
CN2
B3P-VH VHR-3N
SK515-N
INVERTER
ELECTRONIC
CURRENT
PROTECTOR
RED
BLACK
BATTERY IN +
BATTERY IN -
FUSE
BATTERY
MONITOR
(OPTIONAL)
ELECTRONIC
THERMOSTAT
DC/DC
converter
INPUT HIGH
VOLTAGE
PROTECTOR
HIGH TEMPERATURE
PROTECTER
BUZZER (OPTIONAL)
LOW TEMPERATURE
PROTECTER
DC 39V FOR 40W
DC 41V FOR 60W
CN4
B2B-EH
EHR-2
BLACK BLACK
EVAPORATOR
THERMISTOR
AMBIENT
THERMISTOR
AMBIENT
THERMISTOR
DC/AC PART
DC 12~32V
FUSE
9

Troubleshooting – Quick Reference
1. Check for supply voltage at rear of the refrigerator. Turn refrigerator ON. The
operating voltage should be between 10.5V and 32V DC. There will be some
variation in these readings depending on the supply voltage.
2. Check for voltage (15V – 25V AC) at compressor
between points A and B (See Figure 10). If voltage
is not within range, refer to Procedure C on page 5.
A
B
Figure 10
3. Take an Ohm reading (1.4 – 3.5W) at compressor
between points A and B (See Figure 11). If Ohm
reading is not within range, refer to Procedure B on
page 4.
A
B
Figure 11
4. Take an Amp reading (1.6 – 3.3 Amps) at the black
wire with the rubber boot (See Figure 12). If amperage is
not within range, refer to Procedure D on page 6.
10
Figure 12
A