heatcraft-refrigeration-p h-im-77d User Manual

Motor Heater

Model

No. of Amps. Amps.

Size

Motors

0.8

0.4

4.1

2.07

1.6

0.8

5.22

2.61

1.6

0.8

6.09

.04

1.0

0.5

9.57

4.78

1.2

5.7

1.0

7.0

1.5

8.5

Part

115 Volt

208-230 Volt

Description

Motor

2500701 2500701

2500701

250201

2500801

25001

2500801

25001

Fan Blade

5101B

2100201

5101B

2100201

5101B

2100201

Fan Guard

5054D

H5028

5054D

H5028

5054D

H5028

Heater

459N

4540N

4541N

4545N

4542N

454N

4544N

4546N

H50097

24700701

24700702

Heater Clip

554J

H5009

554J

Defrost Control

5709L

Mount

91179001

2101401

91179001

2101401

91179001

2101401

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.off.

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..

off,.and.closes.switch.“B,”.thereby.permitting.current.to.flow.to..

the.heater.

3.. The.heater.recessed.in.slots,.gives.up.heat.directly.to.the.fins.of.the..

evaporator...This.heat.raises.coil.and.refrigerant.temperature...

to.32

F.causing.the.frost.to.melt.

4.. Frost.on.the.evaporator.is.melted.and.defrost.water.drips.into.the..

heated.drain.pan.and.flows.down.the.drain.

5.. When.frost.has.completely.melted.from.the.coil,.the.coil.starts.to..

warm.up.beyond.32

Step “C” - Coil Re-Cooling Cycle

1.. When.the.coil.warms.up.to.55

F,.the.defrost.termination.thermostat..

closes.which.allows.the.current.to.flow.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.off.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.35

F,.the.fan.control.switch..

closes...This.allows.current.to.flow.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.35

F..If.box.is.still..

comparatively.warm.(60

F).when.the.fan.starts,.then.blowing.this..

warm.air.over.the.coil.may.cause.it.to.warm.up.to.55

F.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 Operation

Typical 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,

field.installed,.or.field.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