Hoshizaki Steelheart Series User manual

Models
Refrigerated Prep Table with Raised Rail
B Series
Steelheart Series
Refrigerated Kitchen Equipment
Service Manual
Number: 73246
Issued: 2-14-2023
hoshizakiamerica.com

2
WARNING
Only qualied service technicians should install and service the appliance. To
obtain the name and phone number of your local Hoshizaki Certied Service
Representative, visit www.hoshizaki.com. No service should be undertaken until
the technician has thoroughly read this Service Manual. Failure to service and
maintain the appliance in accordance with this manual will adversely affect safety,
performance, component life, and warranty coverage. Proper installation is the
responsibility of the installer. Product failure or property damage due to improper
installation is not covered under warranty.
Hoshizaki provides this manual primarily to assist qualied service technicians in the
service of the appliance.
Should the reader have any questions or concerns which have not been satisfactorily
addressed, please call, send an e-mail message, or write to the Hoshizaki Technical
Support Department for assistance.
Phone: [phone]
Fax: [phone]
E-mail: [email protected]
618 Highway 74 South
Peachtree City, GA 30269
Attn: Hoshizaki Technical Support Department
Web Site: www.hoshizaki.com
NOTE: To expedite assistance, all correspondence/communication MUST include the
following information:
• Model Number
• Serial Number
• Complete and detailed explanation of the problem.

3
IMPORTANT
This manual should be read carefully before the appliance is serviced. Read
the warnings and guidelines contained in this booklet carefully as they provide
essential information for the continued safe use, service, and maintenance of the
appliance. Retain this booklet for any further reference that may be necessary.
CONTENTS
Important Safety Information ................................................................................................. 4
I. Construction and Refrigeration Circuit Diagram ................................................................. 8
A. Construction.................................................................................................................. 8
B. Refrigeration Circuit Diagram........................................................................................ 9
II. Sequence of Operation and Service Diagnosis............................................................... 10
A. Sequence of Operation Flow Chart ............................................................................ 10
B. Service Diagnosis ....................................................................................................... 12
C. Thermistor Check........................................................................................................ 19
D. Diagnostic Table.......................................................................................................... 20
III. Controls and Adjustments ............................................................................................. 22
A. Control Modules.......................................................................................................... 23
B. Temperature ................................................................................................................ 26
1. Default Temperature Settings................................................................................... 26
2. Temperature Setpoint .............................................................................................. 26
3. Adjusting the Temperature Setpoint for Rail Area Cooling....................................... 26
4a. Cabinet Temperature Control - Cabinet Control Module 4A7178-01...................... 27
4b. Cabinet Temperature Control - Cabinet Control Module 4A7053-01...................... 29
C. Manual Defrost............................................................................................................ 31
D. Cabinet Control Alarm Safeties ................................................................................... 31
1a. Cabinet Control Module: 4A7178-01...................................................................... 31
1b. Cabinet Control Module: 4a7053-01 ...................................................................... 32
E. Safety Devices ............................................................................................................ 32
IV. Refrigeration Circuit and Component Service Information.............................................. 33
A. Refrigeration Circuit Service Information .................................................................... 35
1. Refrigerant Recovery............................................................................................... 35
2. Brazing .................................................................................................................... 36
3. Evacuation............................................................................................................... 36
B. Component Service Information.................................................................................. 38
V. Maintenance .................................................................................................................... 39
VI. Preparing the Appliance for Periods of Non-Use ............................................................ 40
VII. Disposal......................................................................................................................... 41
VIII. Technical Information.................................................................................................... 42
A. Electrical and Refrigerant Data ................................................................................... 42
B. Wiring Diagrams.......................................................................................................... 43

4
DANGER
Risk of Fire or Explosion
Flammable Refrigerant Used
• Follow handling instructions carefully
in compliance with U.S. government
regulations.
• Do not use mechanical devices to defrost.
• Do not puncture refrigerant tubing. Risk
of re or explosion due to puncture
of refrigerant tubing; follow handling
instructions carefully.
• Component parts shall be replaced with
like components.
• Servicing shall be done by factory
authorized service personnel to minimize
the risk of possible ignition due to incorrect
parts or improper service.
• Consult instruction manual/ service
manual before attempting to install or
service this product. All safety precautions
must be followed.
• Dispose of properly in accordance with
federal or local regulations.
• Do not place any potential ignition sources
in or near the appliance.
Important Safety Information
Throughout this manual, notices appear to bring your attention to situations which could
result in death, serious injury, damage to the appliance, or damage to property.
DANGER Indicates a hazardous situation that, if not avoided, will result in
death or serious injury.
WARNING Indicates a hazardous situation that, if not avoided, could result
in death or serious injury.
NOTICE Indicates a situation that, if not avoided, could result in damage
to the appliance or property.
IMPORTANT Indicates important information about the use and care of the
appliance.
Risque De Feu Ou D'Explosion
Le Frigorigène Est Inammable
• Suivre attentivement les instructions
de manipulation conformément à la
réglementation gouvernementale.
• Ne pas utiliser d'appareils mécaniques
pour dégivrer le réfrigérateur.
• Ne pas perforer la tubulure contenant le
frigorigène. Risque de feu ou d'explosion
si la tubulure contenant le frigorigène
est perforée; suivre les instructions de
manutention avec soin.
• Les pièces des composants doivent être
remplacées par des pièces et accessoires
équivalents.
• L’entretien doit être effectué par le
personnel de service autorisé par le
fabricant an de minimiser les risques
d’inammation attribuables à l’installation
d’une pièce inadéquate ou à la mauvaise
exécution du service.
• Consulter le manuel du propriétaire/
guide de réparation avant de tenter une
réparation. Toutes les mesures de sécurité
doivent être respectées.
• Éliminer conformément aux règlements
fédéraux ou locaux.
• Ne placez aucune source d’inammation
potentielle dans ou près de l’appareil.

5
WARNING
The appliance should be destined only to
the use for which it has been expressly
conceived. Any other use should be
considered improper and therefore
dangerous. The manufacturer cannot be
held responsible for injury or damage
resulting from improper, incorrect, and
unreasonable use. Failure to install,
operate, and maintain the appliance
in accordance with this manual will
adversely affect safety, performance,
component life, and warranty coverage.
To reduce the risk of death, electric
shock, serious injury, or re, follow
basic precautions including the
following:
• Only qualied service technicians should
install and service the appliance.
• Wear appropriate personal protective
equipment (PPE) when servicing the
appliance.
• The appliance must be installed in
accordance with applicable national,
state, and local codes and regulations.
• Appliance is heavy. Use care when lifting
or positioning. Work in pairs when needed
to prevent injury or damage. Do not lift
using the top section or the doors/drawers.
• To reduce the risk of electric shock, do not
touch the plug with damp hands.
• Unplug the appliance before servicing.
• The appliance requires an independent
power supply of proper capacity. See the
nameplate for electrical specications.
Failure to use an independent power
supply of proper capacity can result in
a tripped breaker, blown fuse, damage
to existing wiring, or component failure.
This could lead to heat generation or re.
• THE APPLIANCE MUST BE
GROUNDED. The appliance is equipped
with a NEMA5-15 three-prong grounding
plug to reduce the risk of potential
shock hazards. It must be plugged into a
properly grounded, independent 3-prong
wall outlet. If the outlet is a 2-prong outlet,
it is your personal responsibility to have
a qualied electrician replace it with a
properly grounded, independent 3-prong
wall outlet. Do not remove the ground
prong from the power cord and do not use
an adapter plug. Failure to follow these
instructions may result in death, electric
shock, or re.
• Do not use an extension cord.
• Do not use an appliance with a damaged
power cord. The power cord should not be
altered, jerked, bundled, weighed down,
pinched, or tangled. Such actions could
result in electric shock or re. To unplug
the appliance, be sure to pull the plug, not
the cord, and do not jerk the cord.
• The GREEN ground wire in the factory
installed power cord is connected to the
appliance. If it becomes necessary to
remove or replace the power cord, be
sure to connect the power cord's ground
wire.
• Do not splash, pour, or spray water
directly onto or into the appliance. This
might cause short circuit, electric shock,
corrosion, or failure.
• Do not make any alterations to the
appliance. Alterations could result in
electric shock, injury, re, or damage to
the appliance.
• The appliance is not intended for use by
persons (including children) with reduced
physical, sensory, or mental capabilities,
or lack of experience and knowledge,
unless they have been given supervision
or instruction concerning use of the
appliance by a person responsible for
their safety.

6
• Do not block air inlets or outlets, otherwise
cooling performance may be reduced.
• Do not tightly pack the cabinet. Allow some
space between items to ensure good air
ow. Also allow space between items and
interior surfaces.
• Do not put warm or hot foods in the cabinet.
Let them cool rst, or they will raise the
cabinet temperature and could deteriorate
other foods in the cabinet or overload the
appliance.
• Food storage and handling must comply
with applicable codes and regulations.
• All foods should be wrapped in plastic lm
or stored in sealed containers. Otherwise
foods may dry up, pass their smells onto
other foods, cause frost to develop, result
in poor appliance performance, or increase
the likelihood of cross-contamination.
Certain dressings and food ingredients,
if not stored in sealed containers, may
accelerate corrosion of the evaporator,
resulting in failure.
• Do not store items near air outlets.
Otherwise, items may freeze up and
crack or break causing a risk of injury or
contamination of other food.
• The entire rail must always be covered
by rail dividers and pans. Otherwise, the
appliance will not cool properly. Use only
pans up to 6"(15cm) deep.
Do not use damaged rail dividers or pans.
• Ingredients must be pre-chilled to 37°F
(3°C) or less before placing in rail.
• The rail is for keeping ingredients cool while
preparing food. If not actively preparing food
for a long period such as overnight, seal
pans with plastic wrap in addition to closing
the rail cover.
• For PR46-D2 models, all 6 casters must be
installed. Otherwise, the appliance may tip,
resulting in injury or damage.
WARNING, continued
• Children should be properly supervised
around the appliance.
• Do not climb, stand, or hang on the
appliance or doors/drawers or allow
children or animals to do so. Do not climb
into the appliance or allow children or
animals to do so. Death or serious injury
could occur or the appliance could be
damaged.
• Be careful not to pinch ngers when
opening and closing the doors/drawers
or rail cover or when handling food pans.
Be careful when opening and closing the
doors/drawers or rail cover when children
are in the area.
• Open and close the doors/drawers and rail
cover with care. Opening the doors/drawers
or rail cover too quickly or forcefully may
cause injury or damage to the appliance or
surrounding equipment.
• Do not use combustible spray or place
volatile or ammable substances in or near
the appliance. They might catch re.
• Keep the area around the appliance clean.
Dirt, dust, or insects in the appliance could
cause harm to individuals or damage to the
equipment.
• Do not throw anything onto the shelves or
load any single shelf with more than 120lb.
(54.5 kg) of product. They might fall off and
cause injury.
• Do not load any single drawer with more
than 150 lb. (68 kg) of product. Depending
on the weight of product in the drawers,
secure the appliance as necessary to
prevent it from overturning. Do not open
more than one drawer at a time.
• The appliance is designed only for
temporary storage of food. Employ sanitary
methods. Use for any other purposes (for
example, storage of chemicals or medical
supplies such as vaccine and serum) could
cause deterioration of stored items.

7
NOTICE
• Protect the oor when moving the
appliance to prevent damage to the oor.
• Keep ventilation openings clear of
obstruction. The factory-installed rear
bumpers must be in place to ensure
proper rear clearance. Blockage of airow
could negatively affect performance and
damage the appliance.
• Do not allow the appliance to bear any
outside weight.
• To prevent deformation or cracks, do not
spray insecticide onto the plastic parts or
let them come into contact with oil.
• To avoid damage to the gasket, use only
the door/drawer handle when opening
and closing.
• Do not leave the doors/drawers open.
• To avoid damage to the top seal, do not lift
the appliance by the top panel or remove
the top panel.
• Do not place anything on top of the rail
hood or rail cover and do not lift the
appliance by the rail hood or rail cover.
The rail hood and rail cover are not
designed to bear any outside weight.
• Do not place anything on the air duct
panel beneath the pans in the rail.
The air duct panel is not load-bearing.

8
I. Construction and Refrigeration Circuit Diagram
A. Construction
1. Refrigerated Prep Table with Raised Rail
Front Panel
Left Side Panel
Rail Cover
Cabinet Control
Module
Model Shown:PR46B
Compressor
Pans
Rail Dividers
Model Shown:PR67B
PTC Relay and
Run Capacitor
Rail Duct
Model Shown: PR93B
Evaporator
Condenser
Condenser
Fan Motor
Rail Light Sensor
Rail Control
Module
Rail Control
Dial
Condenser
Air Filter

9
B. Refrigeration Circuit Diagram
Evaporator Fan(s)
(quantity depends on model) Evaporator
Compressor
Drier
Condenser
Defrost Heater Capillary Tube
Defrost Safety
Thermostat
Defrost Thermistor
Heat
Exchanger
Condenser Fan
Cabinet Fan(s)
(quantity depends on model)

10
II. Sequence of Operation and Service Diagnosis
A. Sequence of Operation Flow Chart
1. Rail Sequence
DTh warms to 41°F (5°C) or 1 hr. maximum DT terminated 3-min. drip off time starts
3. Cool Down Restart
Rail Sequence Flow Chart Day and Night Mode
Legend: CabFMR-cabinet fan motor relay Comp-compressor ConFM-condenser fan motor DH-defrost heater DOT-drip off time DT-defrost timer DTh-defrost thermistor EvapFM-evaporator fan motor RTh-Rail Thermistor
1. Startup/Cool Down 2. Cool Down Achieved
*Comp energized ConFM energized EvapFM energized *CabFMR energized
RTh in control
Slight Delay at Startup
RTh cools to 3.6°F (2°C) below setpoint
RTh warms to 3.6°F (2°C) above setpoint
4. Defrost Initiation
EvapFM energized *CabFMR energized
*Comp de-energized
ConFM de-energized
5. Defrost Termination
and drip off time
* Note:
a) 2-min. minimum Comp on timer starts when Comp energizes b) 2-min. minimum Comp off timer starts when Comp de-energizes c) 5-min. minimum defrost time d) 1-hr. maximum defrost time e) 3-min. Comp/ConFM delay timer starts when defrost termination temperature is met (drip off time (DOT)) f) After DOT, DTh achieves 36°F (2.2°C) (fan delay after defrost), then EvapFM energizes g) CabFMR energizes on same circuit as EvapFM(s)
DTh in control
*DH energized Comp de-energized ConFM de-energized EvapFM de-energized *CabFMR de-energized
2-min. Comp off timer starts
2-min. Comp on timer starts
*DH de-energized
DOT starts 6-hr. DT resets
6-hr. DT terminates
Rail Factory Default Setpoint: Rail Control Dial Position: 5 Day Mode - Rail Cover Open: 27°F (-2.8°C) Night Mode - Rail Cover Closed: 35 °F (1.7°C)
Cycle Steps
Power on
6. EvapFM Delay
*Comp energized ConFM energized
3-min. drip off time terminates
DTh cools to 36°F (2.2°C) *EvapFM energized *CabFMR energized
5-min. minimum and 1-hr. maximum DT starts

11
CTh cools to
1.8°F (1°C)
below setpoint or
RCM in defrost
2. Cabinet Sequence
3. Cool Down Restart
Cabinet Sequence Flow Chart
Legend:
CabFM-cabinet fan motor
CabFMR-cabinet fan motor relay
CCM-cabinet control module
CTh-cabinet thermistor
RCM-rail control module
1. Startup/Cool Down 2. Cool Down Achieved
CTh above setpoint
RCM not in Defrost
CTh warms
to 1.8°F (1°C)
above setpoint and
RCM not in defrost
*CabFM de-energized
*CabFMR de-energized
Cabinet Factory Default Setpoint:
Cabinet Control Module: 35°F (1.7°C)
Cabinet Fan Motor(s) relay energized through rail control module
Cycle Steps
Power on
*Note:
a) RCM de-energizes CabFMR when rail is in defrost.
b) CabFM(s) are energized when the CCM cooling icon is on and
CabFMR is energized. The cooling icon represents a call for cooling
from the CTh. When displayed, CCM provides 115VAC to CabFMR
for CabFM operation. CabFMR only energizes when EvapFM(s) are
energized through the RCM. The CCM cooling icon may be on when
the CabFMR is not energized due to the appliance being in defrost.
*CabFM energized
*CabFMR energized

12
B. Service Diagnosis
DANGER
Risk of Fire or Explosion
Flammable Refrigerant Used
• Follow handling instructions carefully
in compliance with U.S. government
regulations.
• Do not use mechanical devices to defrost.
• Do not puncture refrigerant tubing. Risk
of re or explosion due to puncture
of refrigerant tubing; follow handling
instructions carefully.
• Component parts shall be replaced with
like components.
• Servicing shall be done by factory
authorized service personnel to minimize
the risk of possible ignition due to
incorrect parts or improper service.
• Consult instruction manual/service manual
before attempting to install or service this
product. All safety precautions must be
followed.
• Dispose of properly in accordance with
federal or local regulations.
• Do not place any potential ignition sources
in or near the appliance.
Risque De Feu Ou D'Explosion
Le Frigorigène Est Inammable
• Suivre attentivement les instructions
de manipulation conformément à la
réglementation gouvernementale.
• Ne pas utiliser d'appareils mécaniques
pour dégivrer le réfrigérateur.
• Ne pas perforer la tubulure contenant le
frigorigène. Risque de feu ou d'explosion
si la tubulure contenant le frigorigène
est perforée; suivre les instructions de
manutention avec soin.
• Les pièces des composants doivent être
remplacées par des pièces et accessoires
équivalents.
• L’entretien doit être effectué par le
personnel de service autorisé par le
fabricant an de minimiser les risques
d’inammation attribuables à l’installation
d’une pièce inadéquate ou à la mauvaise
exécution du service.
• Consulter le manuel du propriétaire/
guide de réparation avant de tenter une
réparation. Toutes les mesures de sécurité
doivent être respectées.
• Éliminer conformément aux règlements
fédéraux ou locaux.
• Ne placez aucune source d’inammation
potentielle dans ou près de l’appareil.

13
WARNING
• The appliance should be diagnosed and repaired only by qualied service
personnel to reduce the risk of death, electric shock, serious injury, or re.
• Wear appropriate personal protective equipment (PPE) when servicing the
appliance.
• Risk of electric shock. Use extreme caution and exercise safe electrical practices.
• Moving parts (e.g., fan blade) can crush and cut. Keep hands clear.
• Appliance is heavy. Use care when lifting or positioning. Work in pairs when needed
to prevent injury or damage.
• Make sure all food zones are clean after the appliance is serviced.
NOTICE
• The appliance is not intended for outdoor use.
• The appliance must not be located in a corrosive environment.
• Normal operating ambient temperature must be within: 45°F to 86°F (7°C to 30°C)
• The appliance must not be located next to ovens, grills, or other high heat
producing equipment.
• The appliance must be a minimum of 1" (3 cm) from side walls.
• The factory-installed rear bumpers must be in place to ensure proper rear
clearance.
• A minimum of 10" (25 cm) clearance above the rail must be provided to allow the
rail cover to open.
The diagnostic procedure is a sequence check that allows you to diagnose the electrical
system and components. Before proceeding, check for correct installation and proper
voltage per nameplate.
Note: When checking voltage (115VAC), always choose a white (W) neutral wire to
establish a good neutral connection.

14
Factory Default Temperature Settings:
a) Rail Control Dial: 5
Day Mode - Rail Cover(s) Open (27°F (-2.8°C))
Night Mode - Rail Cover(s) Closed (35°F (1.7°C))
b) Cabinet Control Module: 35°F (1.7°C)
c) Display Scale: °F
Note: There is a minimum 2-min. Comp on time and 2-min. Comp off time.
For further details, see "III. Controls and Adjustments."
1) Unplug the appliance from the electrical outlet.
2) Remove the front panel and left side panel.
3) Plug the appliance back into the electrical outlet. 6-hr. defrost timer starts.
4) Startup/Cool Down – Rail and cabinet temperature above setpoint. RCD, RTh and CTh
are calling for cooling. Comp, ConFM, EvapFM(s), CabFM(s) and CabFMR energize.
Cabinet temperature and cooling icon are displayed on the CCM.
a) RTh, RCD, and RCM Diagnosis: Day Mode: With rail cover(s) open and RTh calling
for cooling, Comp, ConFM, EvapFM(s), and CabFMR energize.
If not, conrm that the RCD is in the correct setting position (5). Next, check the
resistance between RCD red and black wires. Resistance value should be between
3.76-5.64K ohm. If RCD is out of range, replace RCD. If RCD is in range and rail
temperature is above setpoint, check RTh. See"II.C. Thermistor Check." If RTh is
out of range, replace RTh. If RTh is in range, check for 115VACat RCM line 2(L)
black (BK) wire to RCM neutral 3(N) white (W) wire . If 115VAC is not present,
check breaker/fuse for an open circuit. Reset or replace as needed. Check for loose
connections on line 2(L) black (BK) wire and neutral 3(N) white (W) wire and power
cord connections. If 115VAC is present at RCM 2(L) black (BK) wire and neutral 3(N)
white (W) wire, check for 115VAC at RCM 1(C) violet (V) wire to RCM neutral 3(N)
white (W) wire. If 115VAC is not present, replace RCM.
b) Comp/ConFM Diagnosis: Comp and ConFM energize. Ifnot, conrm 115VAC at
RCM 1(C) violet (V) wire. Next, check for 115VAC from both sides of Comp external
protector red (R) wire and Comp terminal to neutral (W) wire. If 115VAC is present
on one side and not the other, allow time for Comp external protector to cool and
reset. If Comp external protector does not reset, replace Comp external protector.
If115VAC is present on both Comp external protector connections (red (R) wire
and Comp terminal) to neutral white (W), check Comp run capacitor, PTC relay,
and Comp motor windings. Replace as needed. If ConFM is not energized, check
ConFM fan blades for binding and motor winding continuity.
c) EvapFMand CabFMR Diagnosis:EvapFM(s) and CabFMR energize.
If EvapFM(s) do not energize, check for 115VAC at RCM5(F) dark blue (DBU)
wire to neutral white (W) wire. If 115VAC is not present and Comp and ConFM are
energized, replace RCM. If 115VAC is present, check EvapFM(s) blades for binding
and EvapFM(s) continuity. If defective, replace EvapFM(s). Conrm 115VAC at
CabFMR dark blue (DBU) wire to neutral white (W) wire. If 115VAC is not present,
check wiring from RCM.

15
d1) Service Diagnosis: Cabinet Control Module: 4A7178-01
PR46B: L-5 to M50052H, M50073K and Later; (-D2): ALL
PR60B: L-5 to M50007H, M50025L and Later; (-D4): ALL
PR67B(-D2)(-D4): ALL
PR93B(-D2)(-D4)(-D6): ALL
CCM, CTh, CabFMR, and CabFM Diagnosis:
CCM and CTh Diagnosis: Cabinet temperature appears on display and when
cabinet temperature is above setpoint, cooling icon ( ) is displayed. If the cabinet
temperature is not displayed, check for 115VAC at CCM line 8(L) black (BK) wire to
7(N) neutral white (W) wire. If 115VAC is not present, check power cord connections
and breaker/fuse. Reset or replace breaker/fuse (if applicable). If 115VAC is present
and display is off, replace CCM. If 115VAC is present and the cabinet temperature is
displayed and cabinet temperature is above setpoint, cooling icon ( ) is displayed.
If not check CTh. See"II.C. Thermistor Check 5) b)." If CTh is out of range, replace
the CTh. If CTh is in range, cabinet temperature is above setpoint, and cooling icon
is not displayed, replace CCM.
CabFMR and CabFM Diagnosis: With CCM cooling icon displayed ( ) (represents
CTh call for cooling) and CabFMR energized, CabFM(s) energize. If not, check for
115VAC at CCM 3(F) yellow (Y) wire to 7(N) neutral white (W) wire. If 115VAC is
not present, replace CCM. If 115VAC is present, conrm 115VAC at CabFMR dark
blue (DBU) wire to neutral white (W) wire. If 115VAC is not present, check RCM.
See "a) RTH, RCD, and RCM Diagnosis." If 115VAC is present, check for 115VAC at
CabFMR white/blue (W/BU) wire. If 115VAC is not present, replace CabFMR. Next,
check for CabFM(s) fan blade binding and continuity of CabFM(s) windings.
If defective, replace CabFM(s).
d2) Service Diagnosis: Cabinet Control Module: 4A7053-01
PR46B: M50053H-M50072H
PR60B: M50008H-M50024H
CCM, CTh, CabFMR, and CabFM Diagnosis:
CCM and CTh Diagnosis: Cabinet temperature appears on display and when
cabinet temperature is above setpoint, cooling icon ( ) is displayed. If the
temperature is not displayed, check for 115VAC at CCM line 2(L) black (BK) wire to
3(N) neutral white (W) wire. If 115VAC is not present, check power cord connections
and breaker/fuse. Reset or replace breaker/fuse (if applicable). If 115VAC is present
and display is off, replace CCM. If 115VAC is present and cabinet temperature
is above setpoint, cooling icon ( ) is displayed. If not, check CTh. See"II.C.
Thermistor Check 5) a)." If CTh is out of range, replace CTh. If CTh is in range,
cabinet temperature is above setpoint, and cooling icon is not displayed, replace
CCM.

16
CabFMR and CabFM Diagnosis: With CCM cooling icon displayed ( ) (represents
CTh call for cooling) and CabFMR energized, CabFM(s) energize. If not, check for
115VAC at CCM 1(DO1) yellow (Y) wire and 3(N) neutral white (W) wire. If 115VAC
is not present, replace CCM. If 115VAC is present, conrm 115VAC at CabFMR
dark blue (DBU) wire to neutral white (W) wire. If 115VAC is not present, check
RCM status for call for cooling. See "a) RTH, RCD, and RCM Diagnosis". If 115VAC
is present, check for 115VAC at CabFMR white/blue (W/BU) wire. If 115VAC is
not present, replace CabFMR. Next, check for CabFM(s) fan blade binding and
continuity of CabFM(s) windings. If defective, replace CabFM(s).
5) Rail Day Mode or Night Mode Cool Down Achieved – RTh cools to 3.6°F (2°C) below
setpoint. Comp, ConFM, EvapFM(s), and CabFMR de-energize.
Diagnosis: Conrm Comp and ConFM de-energize. Ifnot, and Comp and ConFM were
energized longer than 2min., check RTh status. See"II.C. Thermistor Check." If RTh is
good and Comp and ConFM were energized longer than 2 min., check for 115VAC at
RCM 1(C) violet (V) wire to neutral 3(N) white(W) wire. If115VAC is present, replace
RCM.
6) RLSen Diagnosis – Day mode or night mode conrmation. Check RCM 0VDC and
5VDC output voltage to RLSen. Note: Small accessory type wires with exposed ends
are needed to access the RCM RLSen connections for VDC readings. Due to different
levels of light intensity luminance levels, the RCM VDC output reading for the RLSen
during day mode (rail cover(s) open) may vary between 0-3VDC.
Day Mode: Open the rail cover(s) exposing the RLSen to light.
Next, check between RCM S4 blue (BU) wire to RCM S4 brown (BR) wire for 0-3VDC.
If 5VDC is present, replace RLSen.
Night mode: Close the rail cover(s) removing light exposure to the RLSen.
Next, check between RCM S4 blue (BU) wire to RCM S4 brown (BR) wire for 5VDC.
If 0-3VDC is present, replace RLSen.
7) Cabinet Cool Down Achieved – CTh cools to 1.8°F (1°C) below setpoint 35°F (1.7°C).
CabFM(s) de-energize. Diagnosis: CabFM(s) de-energize. If not, check CTh status.
See"II.C. Thermistor Check." If CTh is good, check for 115VAC at CCM 3(F) yellow (Y)
wire to neutral 7(N) white (W) wire. If115VAC is present, replace CCM.
8) Defrost – 6-hr. time/temperature defrost initiation terminates, defrost starts. If energized,
Comp, ConFM, EvapFM(s), CabFMR, CabFM(s) de-energize. DHenergizes. There is a
5-min. minimum defrost time, 1-hr. maximum defrost time,
6-hr. minimum and maximum defrost interval.
1a) Time/Temperature Initiation: 6-hr. time/temperature defrost initiation terminates,
defrost starts. Comp, ConFM, EvapFM(s), CabFMR, CabFM(s) de-energize.
DHenergizes.

17
Clockwise Counterclockwise
Control Knob
Fig. 1
12 o'clock 12 o'clock
1b) Manual-Initiation: To initiate or terminate a manual defrost cycle: Turn the rail
control dial clockwise to put the rail control dial 9 setting in the 12 o'clock position,
pause for 3 to 5 sec., then turn the rail control dial counterclockwise to any position
below setting 7 in the 12 o'clock position. Defrost initiates or terminates within
5 sec. Note: When defrost is manually initiated it continues through the normal
defrost cycle unless manually terminated. Compressor must be on for a minimum of
2 min. to initiate defrost and off for a minimum of 2 min. to terminate defrost.
2) Defrost-Termination:
(1) DTh warms to 41°F (5°C). DH de-energizes. 3-min. drip off time starts.
(2) 3-min. drip off time terminates. Comp and ConFM energize. If DTh is at
36°F(2.2°C) or lower, EvapFM/CabFM(s) energize. 6-hr. defrost interval timer
resets. Note: If DTh is 37°F (3°C) or higher when 3-min. drip off time terminates,
EvapFM/CabFM(s) remain off until DTh is 36°F(2.2°C) or lower.
Defrost Diagnosis:
1a) Defrost Time/Temperature Initiation Diagnosis: 6-hr. defrost timer terminates.
RCM checks DTh status. If DTh is at or below 41°F (5°C), defrost starts. Comp,
ConFM, EvapFM(s), CabFMR and CabFM(s) de-energize. If 6-hr. defrost timer
terminates and defrost does not start, check DTh. See"II.C. Thermistor Check."
Replace if needed. If DTh is at or below 41°F (5°C) and defrost does not start,
replace RCM. If DTh is at or above 42°F (5.5°C), RCM continues in cooling mode.
1b) Defrost Manual-Initiation Diagnosis: Turn the rail control dial clockwise to put the
rail control dial 9 setting in the 12 o'clock position, pause for 3 to 5 sec., then turn
the rail control dial counterclockwise to any position below rail control dial setting
7 in the 12 o'clock position. Defrost initiates or terminates within 5 sec. If not, replace
RCM and RCD.
Note: Compressor must be on for a minimum of 2 min. to initiate defrost and off for a
minimum of 2 min. to terminate defrost.
Check the following:
(1) DH Diagnosis: Conrm DH energizes. If not, check for 115VAC at RCM 4(H)
red (R) wire to neutral white (W) wire. If 115VAC is not present, replace RCM.
If115VAC is present, check continuity of DST. If open, let cool and reset.
If DST does not close, replace DST. IfDST is closed, check DH amp draw and
continuity. Replace if necessary.
(2) Comp and ConFM Diagnosis: Conrm Comp and ConFM de-energize.
If not, check for 115VAC at RCM 1(C) violet (V) wire to neutralwhite (W) wire.
If115VAC is present, replace RCM.
(3) RCM and CabFMR Diagnosis: Conrm EvapFM(s), CabFMR, and CabFM(s)
de-energize. If not, check for 115VAC at RCM 5(F) dark blue (DBU) wire to
neutral white (W) wire. If 115VAC is present, replace RCM. If 115VAC is not
present and CabFM(s) continue, check for 115VAC at CabFMR white/blue
(W/DBU) wire to neutral white (W) wire. If 115VAC is present (cooling icon on),
replace CabFMR.

18
2) Termination Diagnosis: There is a 5 min. minimum defrost time and a 1 hr.
maximum defrost time. Has 5-min. minimum defrost timer terminated? Conrm DTh
status. See "II.C. Thermistor Check."
(1) RCM, DTh, and DH Diagnosis:If5-min. minimum defrost timer has terminated,
has DTh warmed to 41°F (5°C)? If not, check DST and DH continuity. Next,
check DH amp draw. If DTh is in proper range, DHde-energizes. Ifnot, replace
RCM. If41°F(5°C) is not achieved within 1 hr., RCM terminates defrost. Once
DH de-energizes or 1-hr. maximum defrost timer terminates, 3-min. drip off time
starts. (conrm)
(2) Comp/CondFM, EvapFM Diagnosis: 3-min. drip off time terminates. Comp,
ConFM energize. If DTh is 37°F (2.8°C) or higher when 3-min. drip off time
terminates, EvapFM(s) remains off until DTh is 36°F(2.2°C) or lower. If not,
conrm RTh is warm enough for Comp, ConFM, and EvapFM(s) operation.
Next, check for 115VAC at RCM 1(C) violet (V) wire to neutralwhite (W) wire.
If115VAC is not present, check RTh status. "II.C.Thermistor Check." If RTh
ohm reading is in proper range and Comp and ConFM do not energize, replace
RCM. If 115VAC is present and Comp does not energize, check Comp external
overload. If open, let it cool and reset. If it does not reset, replace external
overload. If closed, check PTC relay, run capacitor, Comp windings for continuity,
or motor binding. If ConFM is not energized, check ConFM fan blades for binding
and winding continuity.
(3) EvapFM Diagnosis: 3-min. Comp/ConFM drip off time terminates. If DTh
is at 36°F(2.2°C) or lower, EvapFM energizes. Ifnot, conrm that DTh is at
36°F(2.2°C) or lower. If not, conrm Comp is on and cooling. See "II.B.5)b)
Comp/ConFM Diagnosis" and "II.C. Thermistor Check." Once 36°F(2.2°C) or
lower is achieved, check for 115VAC at RCM5(F) dark blue (DBU) wire to neutral
white (W) wire. If 115VAC is not present, replace RCM. If 115VAC is present,
and EvapFM(s) are not energized, check EvapFM(s) blades for binding and
EvapFM(s) windings continuity.
(4) CabFM Diagnosis: 3-min. drip off time terminates. If DTh is at 36°F(2.2°C) or
lower, CabFMR energizes. If not, check for 115VAC at CabFMR dark blue (DBU)
wire to neutral (W) wire. If 115VAC is not present and DTh is at 36°F(2.2°C)
or lower, replace RCM. If 115VAC is present and CabFM(s) are not energized,
check for 115VAC at CabFMR yellow (Y) wire to neutral white (W) wire. If 115VAC
is not present, check temperature at CTh. CabFM(s) de-energize when CTh is
below CCM setpoint. Once CTh temperature reaches 1.8°F (1°C) above setpoint,
check for 115VAC at CCM 3(F) yellow (Y) wire to neutral white (W) wire. If
115V is not present, replace CCM. If 115VAC is present and CabFM(s) are not
energized, check CabFM(s) blades for binding and CabFM(s) winding continuity.
If there is no continuity, replace CabFM(s).
Legend: CabFM–cabinet fan motor; CabFMR–cabinet fan motor relay; CCM–cabinet
control module; Comp–compressor; ConFM–condenser fan motor; CTh–cabinet
thermistor; DH–defrost heater; DST–defrost safety thermostat; DTh–defrost
thermistor; EvapFM–evaporator fan motors; RCD-rail control dial; RCM–rail control
module; RLSen-rail light sensor; RTh–rail thermistor

19
C. Thermistor Check
This appliance utilizes 3 thermistors: Rail thermistor, cabinet thermistor, and defrost
thermistor. The rail thermistor is used for rail temperature control, the cabinet thermistor
is used for cabinet temperature control and the defrost thermistor is used for defrost
termination (41°F (5°C)). The defrost thermistor is also used for evaporator fan motor/
cabinet fan motor initiation after defrost (36°F(2.2°C) or lower). Thermistor resistance
varies depending on temperature. The rail control module monitors the rail and defrost
thermistors, while the cabinet control module monitors the cabinet thermistor.
To check thermistor resistance, follow the steps below.
1) Unplug the appliance.
2) Remove the front panel.
3) Disconnect and remove the thermistor in question.
4) Immerse the thermistor sensor portion in a glass containing ice and water for 2 to 3 min.
5) Check the resistance between the wires at the thermistor connector. If outside the
normal reading, replace the thermistor.
Cabinet Control Module: 4A7178-01
PR46B: L-5 to M50052H, M50073K and Later; (-D2): ALL
PR60B: L-5 to M50007H, M50025L and Later; (-D4): ALL
PR67B(-D2)(-D4): ALL
PR93B(-D2)(-D4)(-D6): ALL
a) Rail and Defrost Thermistor - 16 to 16.7 kΩ
b) Cabinet Thermistor - 25 to 27 kΩ
Cabinet Control Module: 4A7053-01
PR46B: M50053H-M50072H
PR60B: M50008H-M50024H
a) Rail , Cabinet, and Defrost Thermistor - 16 to 16.7 kΩ
6) Reconnect and replace the thermistor in its correct position.
7) Plug the appliance back in.

20
D. Diagnostic Table
Check for correct appliance installation per the instruction manual and proper voltage
per appliance nameplate.
1a. Appliance Not Cooling - Rail Area
Appliance Not Cooling - Rail Area - Possible Cause
1. Power Supply a) Unplugged, blown fuse, or tripped or defective circuit breaker.
b) Loose connection.
c) Not within specications.
2. Power Cord and Plug a) Loose connection.
b) Defective.
3. Wiring a) Loose connection or open.
b) Faulty.
4. Rail Control Module a) In alarm (LED ashing red).
b) In defrost.
c) Defective.
5. Rail Control Dial a) Set too warm.
b) Defective.
6. Rail Thermistor
See "II.C. Thermistor Check" a) Loose, disconnected, or out of position.
b) Defective.
7Rail Light Sensor a) Defective. Stuck in night mode while rail lids open (Day mode).
See "II.B.6. RLSen Diagnosis."
8. Compressor External Protector a) Dirty condenser.
b) Condenser fan motor not operating.
c) Defective.
d) PTC relay defective.
e) Low charge.
f) Run capacitor (if applicable) defective.
9. Compressor a) Defective.
10. Condenser Fan Motor a) Fan blade binding.
b) Defective.
11. Condenser a) Dirty.
12. Evaporator Fan Motor a) Defective.
b) Fan Blade Binding.
13. Evaporator a) Dirty or frozen up. See "II.D.2. Evaporator is Frozen Up."
14. Refrigerant/Refrigerant Lines a) Gas leak.
a) Refrigerant lines or components restricted.
15. Rail Air Duct Panel a) Misaligned or missing.
16. Pans and Rail Dividers a) Misaligned with gaps in the rail area.
1 7. Defrost Heater a) Rail Control Module defective.