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11.5
ELECTRONIC CONTROL OPERATION
This unit is equipped with an electronic temperature control. The control parameters are set at the factory and cannot be
manually changed in the field. The pre set control parameters are listed on the chart in the Settings Chart below.
Operation
The control uses two sensors, one located in the air stream and one located on the evaporator coil. The sensor
located in the air stream is referred to as the temperature control sensor. The sensor located on the evaporator coil
is referred to as the defrost probe.
The temperature control sensor is located on the plastic tub behind the evaporator coil to the left in the cold air
stream. The sensor location is critical for proper operation on the unit. Do not move or relocate this sensor.
The coil sensor is strapped to the evaporator coil. This sensor location is critical for proper operation of the unit.
Do not move or relocate this sensor.
The temperature control is set to cut in at 39°F (3.9°C). The Temp control cuts out at 26°F (-3.3°C) at the coldest
setting “9” and 36°F (2.2°C) at the warmest setting “1”.
See “Error! Reference source not found.” on page Error! Bookmark not defined. for more details on using
the control.
Defrost Cycle
The control is programmed to initiate defrost via two different methods. There are 3 programmed defrost cycles in
the case which will initiate a defrost cycle every 8 hours. The unit does not have a time clock so the defrost cycles
cannot be set for any specific time of day.
The unit also has an ‘On demand’ defrost feature that will initiate a defrost when the temperature differential
between the evaporator temperature and the air temperature is more than 20°F (11.1°C) for 5 minutes after 30
minutes into the refrigeration cycle (e.g. if the air stream probe measures 42°F/5.6°C or greater and the defrost
probe measures 20°F/-6.7°C or lower for five minutes). Once initiated the defrost cycle will terminate when
evaporator coil sensor reaches 43°F (6.1°C).
If a manual defrost is required, one can be initiated by pressing and holding the down arrow for three (3) seconds.
This is typically unnecessary and should only be performed if special circumstances require it.
11.6
CONTROL PARAMETERS
Table 2 - Control Parameters
Parameter Description SSRPF52,SRVS42
Control Setpoint
1
2
3
4
5
6
7
8
9
Compressor Cut out [°F] 36.0
34.7
33.5
32.2
31.0
29.7
28.5
27.2
26.0
Compressor Cut in [°F]
39.0°
Compressor Min On Time
10 min (5 MIN ON SSRVS33)
Compressor Min Off Time
3 min
Compressor Max Run Time
90 min
Defrost Termination Temp [°F]
43.0
Time to first defrost
8 hr.
Time to subsequent defrost
8 hr.
Maximum Defrost duration
30 min
Defrost on demand differential [°F]
26.0 (25.0 MIN ON SSRVS33)
Delay for defrost on demand
5 min
Time delay to the next defrost on demand
30 min
