23
E. Compressor Thermal Overload and Short Cycle Protection
1. Compressor Thermal Overload:
When a temperature or amperage value is above the
limit specified by the compressor manufacturer, a thermal overload activates, turning off
the compressor. The compressor restarts when the thermal overload resets.
• Compressor thermal overload resets automatically.
• If the condenser fan is operating and the compressor is off, it is most likely that the
thermal overload opened.
2. Short Cycle Protection:
There is a 2.5-minute compressor delay at start up and a
2.5-minute mandatory on time.
Any time the compressor turns off, it will remain off for a minimum of 2.5 minutes.
Any time the compressor starts, it will remain on for a minimum of 2.5 minutes.
Note: Time may vary with high pressure switch or thermal overload activation.
F. Perimeter Heater
This unit is equipped with a perimeter heater. The perimeter heater is controlled by
the perimeter heater switch located on the control box. To help prevent the formation
of condensation on the front frame, turn the perimeter heater on (perimeter heater
switch red marking visible). When on, the perimeter heater cycles on and off with the
compressor. If operating the unit under conditions where condensation does not form,
this heater may be turned off (perimeter heater switch red marking hidden).
G. Thermistors
The cabinet thermistor is used for cabinet temperature control and the defrost thermistor
is used for initiation and defrost termination. Thermistor resistance varies depending on
temperature. The control board monitors the resistance to control system operation. No
adjustment is required. For further details, see "IV.C. Thermistor Check."
