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4-48 Alarm Codes, Descriptions and Corrective Actions µP-D Controller

CSR-20 & CSR-40, September 1999

Code Description Corrective Action

06 Humidity Sensor Error • Check the sensor by selecting it using the View

(Check Alarm) menu. 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 the sensor by substitution. Be sure the sen-

range; or appears to be open or shorted. sor polarity is correct.

• Continuity check circuit wiring using a high quality

ohmmeter. Be sure to maintain the correct polarity.

NOTE: Do NOT use a test light or other instru-

ment; or controller damage may result.

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.

• Sensor Check test detected an out-of-range

condition. • Continuity check circuit wiring using a high quality

multimeter. Be sure to maintain the correct polarity

• This sensor REQUIRES ice bath calibration or or the sensor will not work

correct sensor grade setup.

NOTE: Do NOT use a test light or other

NOTE: If the Return Air sensor is the instrument; or controller damage may result.

controlling sensor when it fails, the

controller continues unit operation

using the Supply Air sensor.

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.

Thermo King CSR-40 Series User Manual

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