Manual Defrost
How to manually start a defrost cycle on the X4-7700
With the unit powered up (START/RUN-OFF switch in the START/RUN position), press the MANUAL DEFROST key.
This procedure may be demonstrated in PC mode, but the unit will not actually enter defrost.
If conditions for defrost are met, the status bar and Box Temperature display will change to "DEFROST". The MessageCenter will display "DEFROST CYCLE STARTED" for 10 seconds. At the completion of the defrost cycle, the MessageCenter returns to the default display.
If conditions are not met, the MessageCenter will display "CANNOT START DEFROST CYCLE" for 5 seconds. This occurs when: • The box temperature is too warm — DTT sensor must be below 40°F (4.4°C) or SAT sensor must be below 45°F (7.2°C) • The engine has not run at least 15 seconds after starting • The unit is in PC mode • The unit is in Pre-Trip • There is an active shutdown alarm
Defrost may also be initiated automatically at preset intervals by the system defrost timer or by the defrost air switch.
Defrost mode terminates when both the DTT and SAT sensors rise higher than 55°F (12.8°C). If the defrost cycle does not end after a maximum of 45 minutes, it will be terminated automatically and alarm 00054 (Defrost Not Complete) will activate.
If alarm 00054 activates, the system will wait 1.5 hours of unit running time before attempting an automatic defrost cycle. Pressing the MANUAL DEFROST key will override this wait and start a defrost cycle immediately, as long as all conditions are met.