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Refrigeration/defrost sequence of operation, Top mount packaged refrigeration system | outdoor, C on tr ollers – Heatcraft Refrigeration Products PRO TOP MOUNT H-IM-82C User Manual

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Top Mount Packaged Refrigeration System | Outdoor

Refrigeration/Defrost Sequence of Operation

The sequence of operation varies depending on the model that has been installed. The three basic models are Low Temperature, Medium
Temperature, and High Temperature models. The particular model can be determined by the seventh digit of the model number. See Tables
1-3 for details and settings.
Control of the refrigeration and defrost system is provided by the Carel controller along with a space (box) temperature sensor and a coil
(defrost) temperature sensor. The controller will control on and off switching for the compressor, condenser fan motor(s) (cycles with the
compressor), evaporator fan motor(s) and electric defrost heaters for electric defrost.
The Carel controller is pre-programmed for all three applications. This is done with the use of the parameter list. The parameter list can be
changed by entering the Carel Controller and changing the “EZY” setting. See page 15.

Status

Compressor

Condenser

Fans

Evaporator

Fans

Defrost

Heaters

Notes

Off

Display alternates “OFF” and Room
Temperature

Off

Off

Off

Off

If unit shows “OFF”, depress
the “^” button and hold for
three seconds.

On

Automatic Defrost on start up

Off

Off

Off

On

If coil temperature is below
65° F. If it is above, defrost is
not initiated. Drip Time and
Freeze Time are ignored.

On

Defrost Sensor reaches 65° F and
defrost is terminated

Off

Off

Off

Off

On

Cooling cycle initiated - Drip Time

Off

Off

Off

Off

System Timer Begins/ 2 min
drip time

On

Drip Time of 2 minutes ends - coil
freeze begins

On

On

Off

Off

Compressor

starts

and

evaporator fans delay for 2
minutes to freeze the coil.

On

Evaporator fans start after 2 min
delay

On

On

On

Off

On

Box Temperature (-10.1° F) is
satisfied

Off

Off

On

Off

On

Box Temperature rises to -8.0° F

On

On

On

Off

2° F Differential, Minimum
Compressor Off time is 4
minutes

On

Defrost Initiated (Manually or 6
hour counter)

Off

Off

Off

On

Electric Defrost

On

Cooling cycle initiated - Drip Time

Off

Off

Off

Off

System Timer Begins/ 2 min
drip time

On

Drip Time of 2 minutes ends - coil
freeze begins

On

On

Off

Off

Compressor starts and
evaporator fans delay for 2
minutes to freeze the coil.

On

Evaporator fans start after 2 min
delay

On

On

On

Off

TABLE 5

Model PTT | Low Temperature Models | EZY SETTING =1

SET POINT IS -10° F

These models are intended for freezer applications and require electric defrost.

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