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14
TRUE
SPEC SERIES: STR, STA & STG
www.truemfg.com
ELECTRONIC TEMPERATURE CONTROLS
LAE ELECTRONIC CONTROL GENERAL SEQUENCE OF OPERATION
1. Cabinet is plugged in.
a. Display will illuminate.
b. Interior light will illuminate on Glass Door Models only. Solid door cabinet lights are controlled by the door switch.
2. After the LAE control preprogrammed time delay of up to 6 minutes, the compressor and evaporator fan(s) will
start if the control is calling for cooling.
a. Control may be already pre-programmed from the factory so at the start of every compressor cycle or during a
defrost cycle, the condenser fan(s) will reverse for 30 seconds to blow dirt off the condensing coil.
3. The LAE control will cycle the compressor but may also cycle evaporator fan(s) on and off determined by the
Set-Point and Differential temperatures.
a. The Set-Point is the adjustable preprogrammed temperature which shuts off the compressor and evaporator fan(s).
This is not the programmed cabinet temperature.
b. The Differential is the non adjustable preprogrammed temperature that is added to the Set-Point temperature that
will restart the compressor and evaporator fan(s).
c. The LAE control is designed to read and display a cabinet temperature not a product temperature.
This cabinet temperature may reflect the refrigeration cycle of the Set-Point and it’s Differential.
The most accurate temperature on a cabinets operation is to verify the product temperature.
Example: If the Set-Point is -9°F/-23°C and the Differential is 10°F/5°C
(Set-Point) -9°F + 10 (Differential) = 1°F
Or
(Set-Point) -23°C + 5 (Differential) = -18°C
The compressor and evaporator fan(s) will cycle off -9°F/-23°C and back on at 1°F/-18°C
4. The LAE control may be preprogrammed to initiate defrost by interval or at specific times of day.
a. At this time the “dEF” will appear on the display and compressor will turn off until a preprogrammed temperature
or duration is reached. During this time for freezers only, evaporator fan(s) will also turn off and the coil heater and
drain tube heaters will also be energized. Some cabinets may also change the rotation of the reversing condenser
fan motor.
b. After the preprogrammed temperature or duration for defrost has been reached there may be a short delay
for both the compressor and evaporator fans to restart. At this time “dEF” may still appear on the display for a
short time.
LAE ELECTRONIC TEMPERATURE CONTROL GENERAL SEQUENCE OF OPERATION
t1 = supply air / return air* (thermostat)
t2 = coil / copper line (defrost)
t3 = return air / supply air* (display)
t3 probe is not installed and / or activated in all applications
with t3 is not installed and / or activated, the display probe is t1.
* STA, STG, STM, STR Models.
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