Thetford NR740 - Manual (Page 8)

DC0040(K), DC0051(K), DE0040, DE0051, DE0240T, DE0251T,
DC0740(X), DE0740(X), DC0751(X), DE0751(X) Models
Refrigerator Service Manual 8
Troubleshooting - Procedure F
Insufficient Cooling
NOTE: Check input voltage before proceeding. Refer to
Procedure A.
If the compressor runs continuously, do the following:
Check the voltage across the fan leads. There will ■
be a slight voltage reading even if the fan isn't opera-
tional. 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.
CAUTION: When servicing the fan, do not
short the wires. Shorting the wires will damage
the power supply.
!
Make sure that the ventilation vents are not blocked. ■
Refer to Procedure I.
Make sure that the auto shut-off device is operational.
■
Refer to Procedure H.
If the reason for insufficient cooling is not found, start
■
with Procedure B.
Replace the cooling unit if:
The compressor is hot to the touch and not vibrating. ■
The compressor vibrates but there is no cooling. ■
Troubleshooting - Procedure G
Refrigerator is Too Cold
If the refrigerator is too cold, do the following:
Adjust the temperature control to a lower setting. Num- ■
ber 1 is the warmest setting; number 5 is the coldest.
Make sure that the thermistor is securely mounted to
■
the evaporator plate.
If you cannot determine a cause, refer to Procedure E.
■
Troubleshooting - Procedure H
Auto Shut-Off Device
NOTE: Only the 12/24V DC and DE/Truck models are
equipped with the auto shut-off device within the
power supply.
Operating the Shut-Off Device
To protect the cooling unit from overheating, the refrigerator
will automatically shut-off when the ambient air temperature is
approximately 110°F (43°C). If shut-off occurs, the refrigerator
will sound an intermittent alarm tone. To stop the alarm, the
refrigerator must be restarted using the following procedure:
Turn the temperature control counterclockwise to the "Off" 1.
position.
Turn the temperature control to the desired setting.
2.
NOTE: The refrigerator will not restart until the ambient
conditions allow for normal operation.
NOTE: To test the shut-off device's functionality, heat the
device with a heat gun. Refer to Figure 9.
AR
T01956
Figure 9. High Temperature Shut-off Device