Heatcraft Refrigeration Products H-IM-77D User Manual download pdf (Page 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 32

F 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 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 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 35

F, 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 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,

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

1 2 3 4 5 6 7 8 9 10 ... 15 16

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Heatcraft Refrigeration Products H-IM-77D User Manual Page 5

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