Before Calling Service
Manitowoc Ice Machine Checklist
If a problem arises during operation of your ice machine, follow the checklist below before calling for service. Routine
adjustments and maintenance procedures are not covered by the warranty.
Problem Possible Cause To Correct
Ice machine does not operate. No electrical power to the ice machine. Replace the fuse/reset the breaker/turn on
main power switch/plug cord into receptacle.
Control Board fuse open
ICE/OFF/CLEAN toggle switch set improperly. Move toggle switch to the ICE position.
8 minute lockout has not expired. Bin level light will flash to indicate 8 minute
lockout has not expired. Refer to Sequence of Operation
Bin level sensor is disconnected or is contacting the ice.
Connect bin level sensor or remove ice contacting probe.
High Pressure Control is open. Clean condenser, check fan motor, check high
pressure control operation.
Gear Motor runs but compressor will not start.
Water reservoir is empty. (Water must contact the water level probe to start the compressor).
Open water service valve or clean float valve screen.
Water level probes out of position Correct water level probe position.
Remotes Only No electrical power to condensing unit. Replace the fuse/reset the breaker/turn on the
main power switch.
Ice machine stops and can be restarted by moving the toggle switch to OFF and back to ICE.
The SafeGuard feature is stopping the ice machine.
Refer to “SafeGuard Feature” in this section
Ice quality is poor. Poor incoming water quality. Contact a qualified service company to test the
quality of the incoming water and check filter.
Water filtration is poor. Replace filter.
Incoming water temperature is above 90°F (32.3°C) Correct water temperature. (Verify check/
mixing valves in other equipment are working properly). Connect the ice machine to a cold water supply.
Water pressure is low. Water pressure must remain between 20 and 80 psig.
Water softener is working improperly (if applicable).
Repair the water softener.
Low ice capacity. Water float valve screen is dirty. Remove and clean the filter screen.
Incoming water supply is shut-off. Open the water service valve.
Water dump valve is leaking. Clean the dump valve.
Water Pressure is low. Water pressure must remain between 20 and 80 psig.
Incoming water temperature is above 90°F (32.2°C)
Correct water temperature. (verify check/ mixing valves in other equipment is working properly)
Water float valve stuck open or leaking. Remove the float valve and clean it.
Air-Cooled Models Only Objects stacked around ice machine, blocking
airflow to condenser. Remove items blocking airflow.
High air temperature around ice machine. Air temperature must not exceed 110°F (43.3°C)
Inadequate clearance around the ice machine. Provide adequate clearance.
The condenser is dirty. Clean the condenser.
Before Calling Service
Section 5
Safeguard Feature
In addition to standard safety controls, your Manitowoc ice machine features built-in SafeGuards. The ice machine will
stop when conditions arise that would cause major component failure.
RESET PROCEDURE
1. Move the ICE/OFF/CLEAN toggle switch to OFF and then back to ICE.
A. If a safeguard feature has stopped the ice machine, it will restart after a short delay.
Proceed to step 2.
B. If the ice machine does not restart, see “Ice Machine Does Not Operate” on previous page.
2. Allow the ice machine to run to determine if the condition is reoccurring.
A. If the ice machine continues to run, the condition has corrected itself. Allow the ice machine to
continue running.
B. If the ice machine stops again, the condition has reoccurred.
SafeGuards
•No Water
•
Gear Motor Speed is Incorrect
•
QF400/QC700/QF800 Only - Discharge line temp. is too high or low during the freeze cycle.
STANDBY MODE
The first time a failure occurs, the ice machine de-energizes and initiates a Standby Mode. The ice
machine will remain off for 60 minutes, then automatically restart to see if the problem reoccurs.
During the Standby Mode the corresponding light flashes continuously (disch temp, water level or speed).
If the same failure keeps occurring, the ice machine will initiate a SafeGuard Mode and remain off until manually
restarted.
SAFEGUARD INDICATOR LIGHTS
During a SafeGuard Mode the corresponding light (disch temp, water level or speed) will flash continuously.
The SafeGuard will remain in memory for 48 hours of ice making time. After 48 hours of ice making time the
SafeGuard will automatically be erased. If power is interrupted during the 48 hours, the timing will resume
when power is applied to the ice machine.
Placing the toggle switch in the OFF position: The corresponding light will flash continuously.
Placing the toggle switch in the ICE position: The light will de-energize and a start-up sequence will initiate.
The corresponding light will flash anytime the toggle switch is placed in the OFF position provided
48 hours of ice making time has not been exceeded.
Manitowoc Ice Machine
Section 5 Before Calling Service
Analyzing Why SafeGuards May Stop the Ice Machine
According to the refrigeration industry, a high percentage of compressor failure are the result of external causes.
These can include flooding or starving expansion valves, dirty condensers, water loss to the ice machine, etc.
SafeGuards protect the ice machine (primarily the compressor) from external failures by stopping ice
machine operation before major component damage occurs.
Refrigeration and electrical component failures may also trip a safeguard. Eliminate all electrical components and
external causes first. If it appears that the refrigeration system is causing the problem, use the charts,
checklists, and other references to determine the cause.
NOTE: The following checklists are designed to assist the service technician in analysis. However, because
there are many possible external problems, do not limit your diagnosis to only the items listed.
No Water Checklist
SAFEGUARD MODES
No Water
During the Freeze cycle if the water level probe opens or remains open for more than 30* continuous seconds, the
ice machine will de-energize the compressor and gear motor, continuously flash the water level light and initiate
a 60 minute Standby Mode.
During the Standby Mode the water level light will continually flash to indicate a Standby Mode.
After the 60 -minute Standby Mode, the ice machine will de-energize the water level light and initiate a start-up
sequence.
WATER CONTACTS THE WATER LEVEL PROBE:
The ice machine continues to make ice.
WATER LEVEL PROBE OPENS OR REMAINS OPEN
FOR MORE THAN 90 CONTINUOUS SECONDS:
The ice machine will start another 60-minute Standby Mode.
The ice machine repeats the above sequence until:
Water contacts the water level probe
or
The toggle switch is moved to the OFF position.
*Note: There are two control boards, early version boards must remain open for 90 seconds before de-
energizing.
INDICATOR LIGHT
Before 48 hours have elapsed:
After a Standby Mode has been initiated the water level
light will flash anytime the toggle switch is placed in the OFF position.
After 48 hours have elapsed:
The SafeGuard will be automatically erased from memory and the water level will not flash.
Possible Problem List Corrective Action List
No water Restore water supply.
Quick disconnect removed from water float valve Restore water supply.
Water float valve screen blocked Clean screen.
Water float valve solenoid coil defective Replace coil (see Water float valve diagnostics).
Water float valve improperly adjusted Adjust valve (see Water level check).
Dump valve leaking Repair or replace dump valve.
Water level probes disconnected or removed Connect and correctly position probes.
Before Calling Service Section 5
Gear Motor Speed
Anytime the motor speed sensor detects the motor
speed (rpm) is below the minimum range for
3 continuous seconds, the ice machine will:
1. De-energize the compressor and/or gear motor.
2. Continuously flash the Gear Motor Speed light.
3. Initiate a 60-minute Standby Mode.
During the Standby Mode the Motor Speed Sensor light
will flash to indicate a Standby Mode.
After the 60-minute Standby Mode, the ice machine will
de-energize the Motor Speed light and initiate a start-up sequence.
Gear motor speed normal:
The ice machine continues to make ice.
Gear motor speed below minimum range for 3 continuous seconds:
The ice machine will start another 60-minute Standby Mode.
If the gear motor speed drops below the minimum range
for 3 continuous seconds during 7 consecutive cycles,
the ice machine will initiate a SafeGuard Mode.
Gear Motor Speed Checklist
During the SafeGuard Mode the Motor Speed Sensor
light will continually flash to indicate a SafeGuard Mode.
The ice machine remains off until:
• The toggle switch is moved from OFF to ICE.
• Line voltage is interrupted and restored.
INDICATOR LIGHT
Before 48 hours have elapsed:
After a Standby Mode has been initiated the Gear Motor
Speed light will flash anytime the toggle switch is placed in the OFF position.
After 48 hours have elapsed:
The SafeGuard will be automatically erased from
memory and the Gear Motor Speed light will not flash.
Possible Problem List Corrective Action List
Low water pressure Verify water pressure is between 20 and 80 psig.
Defective motor speed sensor Replace motor speed sensor.
Defective motor Replace motor.
Defective coupler Replace coupler.
Defective evaporator/auger assembly Replace evaporator assembly.
Low voltage Verify voltage is within
± 10% of nameplate voltage.
Ice frozen to auger/evaporator Allow evaporator to thaw.
Manitowoc Ice Machine Section 5
Before Calling Service
Temperature is Too High or LowQF400/QC700/QF800
The temperature sensor (thermistor) is mounted on the
compressor discharge line. The temperature sensor
provides input to the control board. The control board
monitors the temperature anytime the compressor is energized.
If the thermistor detects 245°F or higher for 15 continuous seconds:
1. The ice machine will de-energize the compressor
and gear motor and initiate a SafeGuard Mode.
2. The control board “Disch Temp” light will continue to flash twice then pause, to indicate the ice machine
has shut off on high temperature.
3. The ice machine will remain off until the toggle switch is moved from ICE to OFF, and back to ICE.
or
Line voltage is interrupted and restored.
If the thermistor detects 155°F or less for 3
continuous minutes:
1. The control board ignores the low temperature limit
for the first 30 minutes of compressor run time.
2. The ice machine will de-energize the compressor
and gear motor, continuously flash the control board
“Disch Temp” light and initiate a 60-minute Standby
Mode.
3. After the 60-minute Standby Mode, the ice machine
will de-energize the “Disch Temp” light and initiate a start-up sequence.
Temperature Sensor Checklist
4. After 30 minutes of compressor run time, the ice
machine will check the discharge line temperature.
Discharge line temperature normal:
The ice machine continues to make ice.
Discharge line temperature below 155°F after 30 minutes of run time:
The ice machine will start another 60-minute Standby Mode.
If the discharge line temperature drops below 155°F for
3 continuous minutes during 7 consecutive cycles the
ice machine will start a SafeGuard Mode.
During the SafeGuard Mode the ”Disch Temp” light will
continually flash to indicate a Safeguard Mode. The ice machine remains off until:
•
The toggle switch is moved from ICE to OFF, then back to ICE.
• Line voltage is interrupted and restored.
INDICATOR LIGHT
Before 48 hours have elapsed:
After a Standby Mode has been initiated the Control
Board “Disch Temp“ light will flash anytime the toggle switch is placed in the OFF position.
After 48 hours have elapsed:
The SafeGuard will be automatically erased from memory
and the “Disch Temp” light will not flash.
Possible Problem List Corrective Action List
Thermistor is not properly insulated Insulate thermistor.
Thermistor loose Secure thermistor to discharge line.
Thermistor mounted in the wrong location Position thermistor on discharge line 6 in. from compressor
discharge port.
Thermistor defective Refer to CHECK PROCEDURE under “Thermistor.”
Flooding expansion valve Replace expansion valve.
Refrigerant overcharge or undercharge Recover and weigh in nameplate charge.
Low ambient temperature Verify ambient temperature remains above 45°F (7.2°C).
Defective compressor Replace compressor.
Insufficient or low water pressure Verify water pressure is between 20 and 80 psig.
