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ELECTRIC DEFROST — 208/230/1/60 — (2) UNIT COOLERS / (1) HEATER CONTACTOR
Sub-circuit fusing or service disconnect switches are not shown but may be required as per the NEC and / or local codes.
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It is the responsibility of the installing contractor to interpret and comply with all applicable electrical codes.
The defrost time clock, block out relay / auxiliary switch and heater contactor are all typically located in the system condensing
unit. All unit cooler power should feed from this unit. When connecting multiple unit cooler defrost heaters to (1) heater con-
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tactor make sure the total heater amp draw does not exceed the resistive amp rating of the contactor. Also be sure the wire
gauge size is adequate to carry the total amp load required.
When using a heater contactor with unit cooler defrost heaters factory wired for single phase remove factory installed jumper
#
between terminals 2 & 3 on TB1 and wire directly to heater contactor as shown above.
When connecting (2) electric defrost unit coolers to (1) defrost timer remove the black wire from the defrost termination / fan
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delay control which is factory wired to terminal 2 - TB2 on unit cooler #2 and cap the wire. This will allow the fan delay on unit
cooler #1 to control the fans on both unit coolers.
When connecting (2) electric defrost unit coolers to (1) defrost timer remove the red wire from the defrost termination / fan de-
lay control which is factory wired to terminal 4 - TB1 on unit cooler #2 and hard wire to a field wire connected to terminal 1 -
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TB2 on unit cooler #1. This will place the (2) defrost termination controls in series so that both units must reach temperature in
order to terminate the defrost cycle.
The room thermostat and liquid line solenoid valve are shown as field installed but may be factory mounted in the unit cooler.
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Make sure the solenoid holding coil is wired for the correct control voltage (115 or 230).
FIELD WIRING DIAGRAMS — TYPICAL
IMPORTANT WIRING NOTES - INSTALLER PLEASE READ CAREFULLY!
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