Service Manual

13
3. UF/WF: Freezer
UF/WF - Freezer Sequence Flow Chart
Legend: Comp-compressor ConFM-condenser fan motor CTh-cabinet thermistor DH-defrost heater DLT-defrost lock-out timer DT-defrost timer DTh-defrost thermistor EvapFM-evaporator fan motor FDD-fan delay after defrost MH-mullion heater PH-perimeter heater
1. Startup/Cool Down
2. Cool Down Achieved
Comp energized ConFM energized EvapFM energized MH energized PH energized 5-hr. DT starts
CTh in control
4. Defrost
Comp de-energized ConFM de-energized EvapFM de-energized MH de-energized PH de-energized
5. Defrost Termination
DTh in control
Defrost Termination: 55°F (°12.7C) achieved or 1 hr. backup defrost timer terminated.
1-hr. DLT terminates
5-hr. DT terminates or Evap. temp. at or below -31°F (-35°C) 5-min. minimum DT starts 1-hr. maximum DT starts DH energized Comp de-energized ConFM de-energized EvapFM de-energized
MH de-energized
PH de-energized
Note:
a) 2-min. minimum Comp on timer starts when Comp energizes b) 3-min. minimum Comp off timer starts when Comp de-energizes c) 5-min. minimum defrost time d) 1-hr. maximum defrost time e) 3-min. Comp/ConFM delay timer starts when defrost termination temperature is met (drip off time (DOT)) f) 1-hr. defrost lock-out time after defrost terminated (DLT) g) 3-min. EvapFM delay timer terminates or DTh reaches 10°F (-12°C) (FDD (fan delay after defrost), then evaporator fan motor energizes.
*
3-min. DOT terminates or Evap Temp. Achieves 10°F (-12°C) (FDD) 1-hr. DLT starts 5-hr. DT starts EvapFM energized
*
Evap. Temp. achieves 55°F (12.7°C) or 1-hr. DT terminates DH de-energized 3-min. DOT starts Comp energized ConFM energized MH energized PH energized
3. Cool Down Restarts
CTh above setpoint CTh cools to setpoint
CTh above
setpoint
*
*
*
* *
*
*
Power on Yellow LED On (10-sec. Delay)
Red, Yellow, and Green LEDs Cycle
Red and Green LEDs on Yellow LED off
Green LED on Red and Yellow LEDs off
*
*
Defrost: Temperature or Time achieved. DTh achieves -31°F(-35°C)
or 5-hr. DT terminates
5-min. minimum and
1-hr. maximum DT starts
6. Drip Off Time
3-min DOT Terminates
*