Troubleshooting; Troubleshooting - Test A; Thermostat On - Compressor Does Not Run; Troubleshooting - Test B, Compressor Resistance - Norcold DC0788 Service Manual

Troubleshooting

WARNING! Perform all troubleshooting tests using a fully charged
!
12 VDC battery. Using other equipment to supply DC voltage may cause
permanent refrigerator compressor failure.

Troubleshooting - Test A,

Thermostat ON - Compressor does not run

1. Perform the "Diagnostic Pre-checks".
2. Verify that the Temperature Control LED is on.
• Yes: Go to next step.
• No: Replace the fuse, test the unit.
3. With the thermostat 6) in the "OFF" position, check the voltage
at the DC connector. Is the voltage between 12.2 VDC and 17
VDC (12 VDC nominal input) or between 25.2 VDC and 31.5
VDC (24 VDC nominal input)?
• Yes: Go to next step.
• No: Go to Step 5
4. Measure the voltage of the Temperature Control between the
brown wire (TP1) and the black wire (TP2).
• 0 VDC - Short circuit - Replace temperature control.
• 5 VDC - Power supply failure - Replace power supply.
• 2 VDC - Normal - See Troubleshooting Test "B".
5. Verify that the battery voltage is 10.5 -32.0 VDC.
• Yes: Go to next step.
• No: Correct voltage.
6. Verify that the DC fuse is intact.
• Yes: Go to Step 8.
• No: Go to next step.
7. Verify that the DC polarity is correct
• Yes: Go to Step 8.
• No: Reverse polarity (red + / white -). Replace DC fuse.
8. Measure the voltage of the Temperature Control between the
black wire (TP2) and the red wire (TP3).
• 0 VDC - Power supply failure - Replace power supply.
• 12 - 32 VDC - Normal - See Troubleshooting Test "B".
DC558

Troubleshooting - Test B, Compressor resistance

1. Perform the "Diagnostic Pre-checks".
2. Remove the black wire (the fl ag connector) from the compres-
sor.
3. At room temperature, measure the resistance of the compres-
sor between the green/yellow ground wire (ground terminal)
and the terminal where the fl ag connector was removed.
• 0 Ohms - Compressor failure - Replace compressor.
• ∞ Ohms - Compressor failure - Replace compressor.
• 1.6 ± 0.5 Ohms - Normal - See Troubleshooting Test "C".
Troubleshooting - Test C, Power supply output
voltage with compressor load
1. Perform the "Diagnostic Pre-checks".
2. Measure the voltage between the green/yellow ground wire
(ground terminal) of the compressor and the black wire inside
the fl ag connector (which is removed from the compressor).
• 14.5 VAC or lower - Power supply failure - Replace power
supply.
• 0 VAC - Power supply failure - Replace power supply.
• 14.5 - 18.0 VAC - Normal - See Troubleshooting Test "D".

Troubleshooting - Test D, Compressor Amp draw

1. Perform the "Diagnostic Pre-checks".
2. Allow the refrigerator to run for three (3) to fi ve (5) minutes and
then measure the amp draw of the compressor. Measure at the
black wire with the fl ag terminal.
• Less than 1.3 Amps - Compressor failure - Replace the
cooling unit.
• 2.1 ± 0.80 Amps - Normal - See Troubleshooting Test "E".
• More than 2.9 Amps - Compressor failure - Replace the
cooling unit.
Troubleshooting - Test E, Evaporator thermistor
temperature and resistance
1. Perform the "Diagnostic Pre-checks".
2. Turn the refrigerator OFF.
3. Disconnect the three (3) pole connector to the evaporator
thermistor.
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