Manual Defrost
How to manually start a defrost cycle on the Vector 8500
With the system 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 completion, 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: • Box temperature is too warm — defrost termination sensor (1DTT) must be below 40°F (4.4°C) or supply air sensor (1SAT) must be below 45°F (7.2°C) • Engine has not run at least 15 seconds after starting • Unit is in PC mode • Unit is in Pretrip • There is an active shutdown alarm
Defrost may also start automatically at preset intervals via the system defrost timer or the defrost air switch. The defrost cycle terminates when the defrost termination temperature (1DTT) rises above 55°F (12.8°C).
If the defrost cycle does not end after a maximum of 45 minutes, it is terminated automatically and alarm 00054 DEFROST NOT COMPLETE will activate. The system will then wait 1.5 hours of unit running time before attempting another 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.
Refer to Section 4.9 for more detailed information on defrost operation.