5

Motor Heater

Model No. of Amps. Amps.

Size Motors A* B* A* B*

09 1 0.8 0.4 4.1 2.07

12 2 1.6 0.8 5.22 2.61

16 2 1.6 0.8 6.09 .04

21 1 1.0 0.5 9.57 4.78

28 - 1.2 - 5.7

5 2 - 1.0 - 7.0

5 - 1.5 - 8.5

Part 115 Volt 208-230 Volt

Description 09 12 16 21 09 12 16 21 28 35 53

Motor 2500701 2500701 2500701 250201 2500801 2500801 2500801 25001 2500801 25001 25001
Fan Blade 5101B 5101B 5101B 2100201 5101B 5101B 5101B 2100201 5101B 2100201 2100201
Fan Guard 5054D 5054D 5054D H5028 5054D 5054D 5054D H5028 5054D H5028 H5028
Heater 459N 4540N 4541N 4545N 4542N 454N 4544N 4546N H50097 24700701 24700702
Heater Clip 554J 554J 554J 554J 554J 554J 554J 554J H5009 554J 554J
Defrost Control 5709L 5709L 5709L 5709L 5709L 5709L 5709L 5709L 5709L 5709L 5709L
Mount 91179001 91179001 91179001 2101401 91179001 91179001 91179001 2101401 91179001 2101401 2101401
Step “A” - Normal Refrigeration Cycle
1.. Power.is.supplied.to.N.and.4.terminals.by.the.timer.
2.. The.fan.delay.and.defrost.termination.thermostat.is.closed.in.the..
. fan.delay.position.and.open.in.the.defrost.termination.position.
3.. The.defrost.heater.is.o.
4.. The.compressor.operates.in.accordance.with.the.demands.of.the..
. refrigeration.system.temperature.and/or.pressure.controls.
5.. The.unit.cooler.fan.operates.continually.
6.. Frost.builds.up.slowly.on.the.evaporator.
Step “B” - Defrost Cycle
1.. Defrosting.of.the.evaporator.is.started.automatically.by.the.timer..
. at.predetermined.times.-.typical.settings.of.the.timer.would.be.1.to..
. 3.defrost.periods.per.24.hours.
2.. The.timer.mechanically.opens.switch.“A”.which.breaks.the.circuit.to..
. the.compressor.and.evaporator.fan.motors,.thereby.shutting.them..
. o,.and.closes.switch.“B,”.thereby.permitting.current.to.ow.to..
. the.heater.
3.. The.heater.recessed.in.slots,.gives.up.heat.directly.to.the.ns.of.the..
. evaporator...This.heat.raises.coil.and.refrigerant.temperature...
. to.32ºF.causing.the.frost.to.melt.
4.. Frost.on.the.evaporator.is.melted.and.defrost.water.drips.into.the..
. heated.drain.pan.and.ows.down.the.drain.
5.. When.frost.has.completely.melted.from.the.coil,.the.coil.starts.to..
. warm.up.beyond.32ºF.
Step “C” - Coil Re-Cooling Cycle
1.. When.the.coil.warms.up.to.55ºF,.the.defrost.termination.thermostat..
. closes.which.allows.the.current.to.ow.to.the.solenoid.in.the.timer,..
. which.then.energizes.and.trips.the.timer.switch.back.to.its.normal..
. position.(switch.“A”.closed,.switch.“B”.open)..The.fan.delay.portion..
. of.this.thermostat.is.now.open.
2.. The.compressor.now.starts.
3.. Then.fan.motors.remain.o.because.the.fan.delay.thermostat.is..
. open..This.prevents.warm.air.from.being.blown.into.the.. .
. refrigerated.space.
4.. The.evaporator.coil.cools.down.approaching.operating.. .
. temperature..Superheated.gas.only.passes.to.the.compressor.
Step “D” - Return to Normal
Refrigeration Operation
1.. When.the.coil.temperature.reaches.35ºF,.the.fan.control.switch..
. closes...This.allows.current.to.ow.to.the.fan.motor.and.the.unit.is..
. now.back.in.operation.as.in.Step.“A.”
IMPORTANT
1.. On.initial.“pull.down”.of.a.warm.box,.the.fan.will.not.start.until.coil..
. temperature.reaches.approximately.35ºF..If.box.is.still.. .
. comparatively.warm.(60ºF).when.the.fan.starts,.then.blowing.this..
. warm.air.over.the.coil.may.cause.it.to.warm.up.to.55ºF.and.thus..
. stop.the.fan..Therefore,.fan.may.recycle.several.times.on.initial..
. “pull.down.”
2.. The.timer.has.an.adjustable.fail-safe.feature.which.will.return.the..
. system.to.the.refrigeration.cycle.at.the.end.of.a.predetermined..
. time.(factory.set.at.24.minutes).if.automatic.control.devices.fail.
3.. Frequent.defrost.periods.are.not.necessary!.The.determining.factor..
. for.number.of.defrosts.per.day.is.the.frost.load..When.frost.“build-.
. up”.results.in.a.loss.of.refrigeration.capacity,.then.a.defrost.is...
. required...One.to.three.defrosts.per.day.are.recommended.
4.. A.low.temperature.thermostatic.expansion.valve.with.pressure..
. limiting.feature.is.desirable.for.use.with.these.units..Such.a.valve..
. prevents.feeding.of.refrigerant.to.the.coil.during.the.defrost.cycle.
Sequence of OperationTypical Wiring Diagram for Thin Profile Electric Defrost Unit Cooler

1.. Use.copper.conductors.only.

2.. Unit.must.be.grounded.

3.. Timer-Paragon.Model.8145-20.may.be.factory.supplied,

. eld.installed,.or.eld.supplied.and.installed.

4.. Fan.delay.and.defrost.termination.-.Red.to.N,.Brown.to.X,

. Black.to.F...Fans.will.not.operate.until.thermostat.resets.

5.. Heater.limit:..Red.to.N,.White.to.H.omitted.on.model.28;

. heater.is.connected.directly.to.N.

6.. *Indicates.electrical.code:.A=115/60/1,.B=208-230/60/1.

Commercial Refrigeration Parts
Replacement Parts