Hoshizaki RTC-120MNA User manual

NO. T069-838
ISSUED: MAY 31, 2011
REVISED: JUN. 16, 2014
HOSHIZAKI
UNDERCOUNTER
REFRIGERATOR/FREEZER
SERVICE MANUAL
MODEL RTC-M_A series
FTC-M_A series

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CONTENTS PAGE
I. GENERAL INFORMATION --------------------------------------------------------------------------1
1. SAFETY INSTRUCTIONS-------------------------------------------------------------------------1
2. DIMENSIONS/SPECIFICATIONS ---------------------------------------------------------------3
[a] RTC-120MNA-------------------------------------------------------------------------------------3
[b] RTC-120MDA-------------------------------------------------------------------------------------4
[c] RTC-150MNA-------------------------------------------------------------------------------------5
[d] RTC-150MDA-------------------------------------------------------------------------------------6
[e] RTC-180MNA-------------------------------------------------------------------------------------7
[f] RTC-180MDA--------------------------------------------------------------------------------------8
[g] FTC-120MNA-------------------------------------------------------------------------------------9
[h] FTC-120MDA----------------------------------------------------------------------------------- 10
[i] FTC-150MNA------------------------------------------------------------------------------------ 11
[j] FTC-150MDA------------------------------------------------------------------------------------ 12
[k] FTC-180MNA ----------------------------------------------------------------------------------- 13
[l] FTC-180MDA------------------------------------------------------------------------------------ 14
II. TECHNICAL INFORMATION--------------------------------------------------------------------- 15
1. WIRING DIAGRAM-------------------------------------------------------------------------------- 15
[a] RTC SERIES ----------------------------------------------------------------------------------- 15
[b] FTC-120MNA, FTC-120MDA, FTC-150MNA------------------------------------------- 16
[c] FTC-150MDA, FTC-180MNA, FTC-180MDA------------------------------------------- 17
2. REFRIGERATION CIRCUIT -------------------------------------------------------------------- 18
[a] RTC SERIES ----------------------------------------------------------------------------------- 18
[b] FTC SERIES------------------------------------------------------------------------------------ 19
3. ELECTRONIC CONTROLS --------------------------------------------------------------------- 20
[a] SET POINT TEMPERATURE -------------------------------------------------------------- 20
[b] CABINET TEMPERATURE DIFFERENTIAL ------------------------------------------- 20
[c] DEFROST CYCLE ---------------------------------------------------------------------------- 20
[d] DEFROST TERMINATION TEMPERATURE------------------------------------------- 20
[e] TEMPERATURE DISPLAY------------------------------------------------------------------ 20
[f] COMPRESSOR SOFT START ------------------------------------------------------------- 21
[g] HIGH PRESSURE SWITCH---------------------------------------------------------------- 21
[h] CHECKING SET POINT TEMPERATURE---------------------------------------------- 22
[i] MANUAL DEFROST--------------------------------------------------------------------------- 22
[j] ERROR CODES -------------------------------------------------------------------------------- 22
4. TIMING CHART ------------------------------------------------------------------------------------ 23
[a] STARTUP - CONTROL ---------------------------------------------------------------------- 23
[b] DEFROST --------------------------------------------------------------------------------------- 24
5. CONTROLLER ------------------------------------------------------------------------------------- 25
[a] RTC SERIES ----------------------------------------------------------------------------------- 25
[b] FTC SERIES------------------------------------------------------------------------------------ 28
III. SERVICE DIAGNOSIS---------------------------------------------------------------------------- 33
1. ERROR CODES ----------------------------------------------------------------------------------- 33
2. FLOWCHART--------------------------------------------------------------------------------------- 34
[a] RTC SERIES ----------------------------------------------------------------------------------- 34
[b] FTC SERIES------------------------------------------------------------------------------------ 36

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3. COMPONENTS ------------------------------------------------------------------------------------ 38
4. CONTROLLER ------------------------------------------------------------------------------------- 40
[a] SERVICING CONTROLLER---------------------------------------------------------------- 40
[b] CHECKING THERMISTOR ----------------------------------------------------------------- 41
IV. REMOVAL AND REPLACEMENT OF COMPONENTS ---------------------------------- 42
1. REFRIGERATION CIRCUIT -------------------------------------------------------------------- 42
[a] REFRIGERANT-------------------------------------------------------------------------------- 42
[b] COMPRESSOR-------------------------------------------------------------------------------- 42
[c] CONDENSER ---------------------------------------------------------------------------------- 44
[d] DRIER -------------------------------------------------------------------------------------------- 44
[e] EVAPORATOR --------------------------------------------------------------------------------- 44
2. ELECTRICAL PARTS----------------------------------------------------------------------------- 45
[a] CONDENSER FAN MOTOR---------------------------------------------------------------- 45
[b] INTERIOR FAN MOTOR -------------------------------------------------------------------- 46
[c] DEFROST HEATER, THERMAL FUSE-------------------------------------------------- 47
[d] INTERIOR THERMISTOR, DEFROST THERMISTOR ------------------------------ 48
[e] CONTROLLER--------------------------------------------------------------------------------- 49
[f] FUSE ---------------------------------------------------------------------------------------------- 49
[g] FORCED DRAIN WATER EVAPORATION PAN -------------------------------------- 49
3. DOOR GASKET------------------------------------------------------------------------------------ 50
[a] REMOVAL --------------------------------------------------------------------------------------- 50
[b] REPLACEMENT------------------------------------------------------------------------------- 50

1
I. GENERAL INFORMATION
1. SAFETY INSTRUCTIONS
The following instructions contain important safety precautions and should be strictly
observed. The terms used here are dened as follows:
WARNING: There is a possibility of death or serious injury to the service person and
a third party or the user due to improper service operations or defects in
serviced products.
CAUTION: There is a possibility of injury to the service person and a third party or the
user or damage to their property* due to improper service operations or
defects in serviced products.
* The term “damage to their property” here refers to extensive damage to household
effects, houses and pets.
WARNING
1. Always ask the user to keep children away from the work area. They may be injured by
tools or disassembled products.
2. When there is no need to energize the unit during disassembly or cleaning, be sure to
unplug the unit or disconnect the main power supply before servicing the unit to prevent
electric shocks.
3. If the unit must be energized for inspection of the electric circuit, use rubber gloves to
avoid contact with any live parts resulting in electric shocks.
4. Keep the following in mind when servicing the refrigeration circuit:
(1) Be sure to recover the refrigerant. Do not discharge it into the atmosphere. It will
affect the environment.
(2) Check for any ames in the vicinity, and ensure good ventilation.
(3) If the refrigerant should leak in servicing, immediately put out any re used in the
vicinity.
(4) When unbrazing the refrigeration circuit connections, check that the circuit is
completely evacuated. The refrigerant may produce a poisonous gas when coming
in contact with an open ame.
(5) Do not braze in an enclosed room to prevent carbon monoxide poisoning.
(6) In case of a refrigerant leak, locate and repair the leaking part completely before
recharging the refrigerant and checking for further leaks. If the leaking part cannot

2
be located, be sure to check again for further leaks after recharging the refrigerant.
Leaked refrigerant may produce a poisonous gas when coming in contact with an
open ame of a gas cooking stove or a fan heater.
(7) Before servicing, check the surface temperature of the refrigeration circuit to
prevent a burn.
5. Keep the following in mind when making electrical connections:
(1) Check for proper earth connections, and repair if necessary to prevent electric
shocks.
(2) Always use service parts intended for the applicable model for replacement
of defective parts. Use proper tools to secure the wiring. Otherwise abnormal
operation or trouble may occur and cause electric leaks or re.
(3) Check for proper part installations, wiring conditions and soldered or solderless
terminal connections to avoid re, heat or electric shocks.
(4) Be sure to replace damaged or deteriorated power cords and lead wires to prevent
re, heat or electric shocks.
(5) Cut-off lead wires must be bound using closed end connectors or the like, with their
closed ends up to avoid entrance of moisture that could lead to electric leaks or
re.
(6) After servicing, always use a megohmmeter (500V DC) to check for the insulation
resistance of at least 1 megohm between the live part (attachment plug) and the
dead metal part (earth terminal).
(7) Do not service the electrical parts with wet hands to prevent electric shocks.
(8) The capacitors used for the compressor and other components may be under high
voltage and should be discharged properly before servicing.
CAUTION
1. After servicing, follow the instructions below:
(1) Always check the unit for proper operation before nishing services.
(2) Be sure to reassemble the parts completely. Loose assembly of such parts as
control box cover may cause entrance of vermins resulting in a short circuit
between terminals and possible ignition.

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2. DIMENSIONS/SPECIFICATIONS
[a] RTC-120MNA

4
[b] RTC-120MDA

5
[c] RTC-150MNA

6
[d] RTC-150MDA

7
[e] RTC-180MNA

8
[f] RTC-180MDA

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[g] FTC-120MNA

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[h] FTC-120MDA

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[i] FTC-150MNA

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[j] FTC-150MDA

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[k] FTC-180MNA

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[l] FTC-180MDA

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II. TECHNICAL INFORMATION
1. WIRING DIAGRAM
[a] RTC SERIES

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[b] FTC-120MNA, FTC-120MDA, FTC-150MNA

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[c] FTC-150MDA, FTC-180MNA, FTC-180MDA