Thermo King CRR-20, Maintenance Manual

Page: 102 / 200

4-48 Alarm Codes, Descriptions and Corrective Actions
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P-D Controller
CRR-20 & CRR-40, September 1999
Code Description Corrective Action
07 Return Air Temperature Sensor Failure • Check the sensor by selecting it using the RET/SUP
(Check Alarm) key (if necessary). If the display shows [- - - -], the
sensor is defective or the circuit is open or shorted.
• Indicates a problem exists with this sensor
or its wiring. The sensor is reading out-of- • Check sensor by substitution. Be sure sensor
range; or appears to be open or shorted. polarity is correct. Replacement sensor MUST be
calibrated or sensor grade set.
• This sensor REQUIRES ice bath calibration or
correct sensor grade setup. • Continuity check circuit wiring using a high quality
multimeter. Be sure to maintain the correct polarity
NOTE: If the Return Air sensor is the or the sensor will not work .
controlling sensor when it fails, the
controller continues unit operation
NOTE: Do NOT use a test light or other instru--
using the Supply Air sensor. ment; or controller damage may result.
09 Evaporator Coil Over Temperature • Check electric heater rod operation using the
(Shutdown Alarm — prevents unit from “AMPS HEATR” test in the Electrical Test submenu.
operating in Heat or Defrost)
• Check evaporator coil sensor using View Menu.
• Evaporator coil has exceeded high
temperature limit. • Check airflow over evaporator coil.
10 High Pressure Cutout • Check for a dirty or restricted condenser coil.
(Check Alarm)
• Check for correct condenser fan operation using
• Indicates the high pressure cutout switch “AMPS CFH” test in the Electrical Test submenu.
has opened and the condition was not
corrected after 5 minutes (fault condition
• Install manifold gauge set and check for correct
prevented unit restart). condenser fan pressure switch operation.
NOTE: Controller display shows “PAUSE • Check fuse F11 on the power module.
ALM10” every 10 seconds while condenser
fan operates to resolve the problem during
• Continuity check high pressure cutout switch
unit shutdown. (identified by blue cable tie) and condenser fan
pressure switch (identified by red cable tie) circuit
• Controller also generates alarm if high wiring using a high quality multimeter.
pressure cutout/restart cycle recurs 3 times
within 30 minutes.
NOTE: Do NOT use a test light or other instru--
ment; or controller damage may result.
• Check for correct water cooled condenser operation
(option).
• Check for jumper on water pressure switch connec-
tors in sensor harness if unit is NOT equipped with a
water cooled condenser (option).
• Check for a defective high pressure cutout switch.