How it Works
Scotsman Ice Machine
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CU1526
Service Manual
62 pgs4.07 Mb0
Installation Manual
18 pgs466.68 Kb0

Scotsman Ice Machine CU1526 Service Manual

Introduction
The design of this cuber is the result of years of experience and testing. Standard features include a removable bin for service and an on-off switch at the front of the cabinet for easy operational control.
Table of Contents
CU1526, CU2026, CU3030
Service Manual
Installation: Product Specifications ..... Page 2
Model Number Description.......... Page 3
Water .....................Page 4
CU1526 and CU2026 Cabinet Layout .... Page 5
CU3030 Cabinet Layout ........... Page 6
Bin Removal ................. Page 7
Plumbing Requirements ........... Page 8
Electrical ................... Page 9
Adjustments .................Page 10
Use and Operation .............. Page 11
Control Switches ............... Page 12
Cuber System Information .......... Page 13
Controller Information ............ Page 14
Component Indicator Light Table ...... Page 15
How It Works - Air Cooled .......... Page 16
How It Works - Water Cooled ........ Page 17
Electrical Sequence - Air or Water Cooled . Page 18
Electrical Component Details ........ Page 20
Electrical Component Details - continued . . Page 21
Refrigeration & Water Systems ....... Page 22
Control Operation .............. Page 23
Control Safeties ............... Page 24
Restarts ...................Page 25
Control Button Use .............. Page 26
Test Mode: .................. Page 27
Service Diagnosis .............. Page 28
Service Diagnosis .............. Page 29
Service Diagnosis .............. Page 30
Cleaning, Sanitation and Maintenance . . . Page 32
Test Procedures - Sensors ......... Page 34
Sensor Testing ................Page 35
Thermistors ................. Page 36
Test Procedures - Loads ........... Page 37
Test Procedures ............... Page 38
Technical Information ............ Page 41
Performance Data, CU1526
Performance Data, CU2026 ......... Page 43
Performance Data, CU3030 ......... Page 44
Wiring Diagram, CU1526 and CU2026 60 Hz up to
Serial Number 12021320013437 ...... Page 45
Wiring Diagram, CU1526 and CU2026 60 Hz after Serial
Number 12021320013437 .......... Page 46
Wiring Diagram, CU3030 60 Hz up to Serial Number
TBD ..................... Page 47
Wiring Diagram, CU3030 60 Hz after Serial Number
TBD ..................... Page 48
Wiring Diagram, CU1526 and CU2026 50 Hz up to
Serial Number 12021320013437 ...... Page 49
Wiring Diagram, CU1526 and CU2026 50 Hz after Serial
Number 12021320013437 .......... Page 50
Wiring Diagram, CU3030 50 Hz up to Serial Number tbd Page 51
Wiring Diagram, CU3030 50 Hz after Serial Number tbd Page 52
Removal and Replacement ......... Page 53
Refrigeration Removal and Replacement Procedures
........................Page 59
Refrigeration Removal and Replacement Procedures
........................Page 62
......... Page 42
Service Diagnosis - Low ice making capacity - air cooled
........................Page 31
Note any Caution or Warning symbols when they appear on the product or in this manual. They indicate potential hazards.
Page 1
CU1526, CU2026, CU3030 Service Manual
Installation: Product Specifications
Location Limitations:
The product is designed to be installed indoors, in a controlled environment. Air cooled models discharge very warm air into the room. Water cooled models discharge warm water into the building’s drain. Space needs to be provided for service access.
Space Limitations
Do not block air flow at the front.
Airflow is in the front left and out the front right. CU3030 also takes air in from below the cabinet.
Environmental Limitations
Minimum Maximum
Air temperature
Water temperature
Water pressure
o
50
F. 100oF.
o
40
F. 100oF.
20 psi 80 psi
Power supply – acceptable voltage ranges
Minimum Maximum
115 volt model 104 volts 126 volts
230 volt model 198 volts 253 volts
Warranty Information
The warranty statement for this product is provided separately from this manual. Refer to it for applicable coverage. In general warranty covers defects in material or workmanship. It does not cover maintenance, corrections to installations, or situations when the machine is operated in circumstances that exceed the limitations printed above.
Air Flow
Product Information
The product is a self contained cuber with bin. That type of machine is designed to be free standing can be built in under the counter.
Page 2
Model Number Description
CU1526, CU2026, CU3030
Service Manual
Example:
CU2026SA-1A
•
C= cuber
•
U=under the counter type
•
20= nominal ice capacity in 10s of pounds
•
26= nominal width of cabinet
•
S= Cube size. S=small or half dice cube.
•
M=medium or full dice cube A=Condenser type. A=air cooled. W=water
•
cooled
-1=115 60 Hz, -32 = 208-230 volt, 60 Hz, -6
•
= 230 volt, 50 Hz A=Series revision code. A=first series
•
Note: In some areas of this manual model numbers may include only the first six characters of the model number, meaning that the cube size, condenser type and voltage differences are not critical to the information listed there.
Product Description & Electrical Requirements
Scotsman ice systems are designed and manufactured with the highest regard for safety and performance.
Scotsman assumes no liability of responsibility of any kind for products manufactured by Scotsman that have been altered in any way, including the use of any part and/or other components not specifically approved by Scotsman.
Scotsman reserves the right to make design changes and/or improvements at any time. Specifications and design are subject to change without notice.
Dimensions w" x d" x h"**
26.62 x 27.5 x 33
26.62 x 27.5 x 33
30.62 x 30 x 33
Table notes: Height is without legs. Medium cube models have the same electrical characteristics as Small. Series revision code omitted. * Or HACR type circuit breakers. ** If not using legs, add .25" for screws below base. Legs add 6 to 6.75 inches, but the 1/4 inch for the screws.
Model
CU1526SA-1 115/60/1 Air 7.7 15
CU1526SW-1 115/60/1 Water 7.7 15
CU2026SA-1 115/60/1 Air 7.2 15
CU2026SW-1 115/60/1 Water 7.2 15
CU2026SA-32 208-230/60/1 Air 3.7 15
CU2026SW-32 208-230/60/1 Water 2.96 15
CU3030SA-1 115/60/1 Air 10.4 15
CU3030SW-1 115/60/1 Water 10.4 15
CU3030SA-32 208-230/60/1 Air 5.54 15
CU3030SW-32 208-230/60/1 Water 4.48 15
Electrical volts/Hz/phase
Condenser
Total Load Amps
Maximum Fuse Size*
Page 3
CU1526, CU2026, CU3030 Service Manual
Water
The quality of the water supplied to the ice machine will have an impact on the time between cleanings and ultimately on the life of the product. Water can contain impurities either in suspension or in solution. Suspended solids can be filtered out. In solution or dissolved solids cannot be filtered, they must be diluted or treated. Water filters are recommended to remove suspended solids. Some filters have treatment in them for suspended solids. Check with a water treatment service for a recommendation.
RO water. This machine can be supplied with Reverse Osmosis water, but the water conductivity must be no less than 10 microSiemens/cm.
Potential for Airborne Contamination
Installing an ice machine near a source of yeast or similar material can result in the need for more frequent sanitation cleanings due to the tendency of these materials to contaminate the machine. Most water filters remove chlorine from the water supply to the machine which contributes to this situation. Testing has shown that using a filter that does not remove chlorine, such as the Scotsman Aqua Patrol, will greatly improve this situation, while the ice making process itself will remove the chlorine from the ice, resulting in no taste or odor impact. Additionally, devices intended to enhance ice machine sanitation, such as the Scotsman Aqua Bullet, can be placed in the machine to keep it cleaner between manual cleanings.
Water purge
Cube ice machines use more water than what ends up in the bin as ice. While most water is used during ice making, a portion is designed to be drained out every cycle to reduce the amount of hard water scale in the machine. That’s known as water purge, and an effective purge can increase the time between needed water system cleaning.
In addition, this product has the capability to automatically vary the amount of water purged based on the purity of the water supplied to it. The water purge rate can also be set manually. Adjustments of purge due to local water conditions are not covered by warranty.
This manual covers several models. The model number on the product is located in two places, on the back dataplate and on the model and serial number tag, located behind the front panel. See the illustration for the dataplate and serial tag locations.
Page 4
CU1526 and CU2026 Cabinet Layout
5.48
13.9
39.0
99.0
22.12
56.2
4.00
MINIMUM
UTILITY
CLEARANCE
10.2
6.00
15.2
22.25
56.5
29.65
75.3
27.5
69.9
4.86
12.3
26.62
67.6
30.04
76.3
15.55
39.5
2.60
6.6
4.85
12.3
6.50
16.5
3.19
8.1
4.32
11
5.92
15
DRAIN
3/4 FPT
COND WATER
REGULATOR
3/8 NPT
(W/C ONLY)
COND DRAIN
1/2 NPT
(W/C ONLY)
POTABLE
WATER INLET
3/8 FLARE
POWER CORD
CU1526, CU2026, CU3030
Service Manual
Page 5
CU1526, CU2026, CU3030
5.30
13.5
39.0
99.0
25.95
65.9
4.69
11.9
30.0
76.2
30.62
77.8
4.00
MINIMUM
UTILITY
CLEARANCE
10.2
6.00
15.2
24.25
61.6
29.63
75.3
6.99
17.7
3.19
8.1
4.33
11
29.36
74.6
2.77
7
4.65
11.8
6.27
15.9
23.82
60.5
DRAIN 3/4 FPT
COND WATER
REGULATOR
3/8 NPT
(W/C ONLY)
COND DRAIN
1/2 NPT
(W/C ONLY)
POTABLE
WATER INLET
3/8 FLARE
POWER CORD
Service Manual
CU3030 Cabinet Layout
Page 6
Bin Removal
The ice storage bin is removable to allow access to the refrigeration system for service.
1. Remove front louvers. Remove left then right.
2. If the machine is in an ice making mode, push and release the Manual Harvest button to release any ice that might be on the evaporator.
3. Push and hold the controller's Off button to shut the machine off.
CU1526, CU2026, CU3030
Service Manual
4. Remove all ice from the bin.
5. Disconnect electrical power.
6. Remove door (open about 1.5" and pull bottom out).
7. Remove the top panel, there are two fasteners under the front corners of the top. Back them out and lift the top up, push back slightly and lift panel up and off the machine..
8. Disconnect the drain tube from the bin drain fitting.
Disconnect hose before moving bin.
Remove bolt to release bin
9. Remove two bolts from the bottom of the bin, one on the left and one on the right.
10. Remove bolt from the back wall of the bin.
Remove bolt to release bin
11. Pull the bin forward and off the chassis.
Page 7
CU1526, CU2026, CU3030 Service Manual
Plumbing Requirements
All models require connection to cold, potable water. A hand actuated valve within sight of the machine is required. Air cooled models have a single 3/8” FPT inlet water connection. Water cooled models have the same inlet fitting plus an additional 3/8” FPT condenser inlet water connection.
Water Filters
If connecting to water filtration, filter only the water to the reservoir, not to the condenser. Install a new cartridge if the filters were used with a prior machine.
All models require drain tubing to be attached to them. Air cooled models have a single ¾” FPT drain fitting in the back of the cabinet. Water cooled models have the same fitting plus an additional ½” FPT drain fitting in the back of the cabinet.
Install new tubing when replacing a prior ice machine, as the tubing will have been sized for the old model and might not be correct for this one.
Note: This NSF listed model has a 1" anti-back flow air gap between the float valve orifice and the highest possible reservoir water level, no back flow device is required for the potable water inlet.
2. Connect drain tubing to drain fittings.
3. Route the drain tubing to building drain. Follow local codes for air gap.
Drain Tubing:
Use rigid drain tubes and route them separately – if water cooled, do not Tee the condenser drain into the reservoir or bin drain.
Vent the reservoir drain. A vertical vent at the back of the drain, extended about 8 - 10" will allow the gravity drain to empty and also keep any surges during draining from discharging water out the vent..
Horizontal runs of drain tubing need a ¼” fall per foot of run for proper draining.
1. Connect water supply to water inlet fittings. 3/8" OD tubing is recommended.
Water Filter (if used)
Water Inlet
Shut off valve
Drain
Tubing
Floor Drain
Follow all applicable codes.
Water Cooled
Supply Location
Bin Drain
Connection
Potable
Water
Connection
Water Cooled
Drain Location
Air Cooled Model Plumbing Connections
Water Cooled Plumbing Connections
Page 8
Electrical
The machine is supplied with a power cord.
This is a cord-connected unit, and must be on a separate power supply. Check the dataplate for the voltage, ampacity and maximum fuse size and per the dataplate use fuses or HACR circuit breakers.
Follow All Local Codes - This Unit Must Be Grounded. Do not use extension cords and do not
disable or by-pass ground prong on electrical plug.
Typical Ice Making Cycle Times (minutes).
Listed times are for clean machines in proper installations. Cycle length at startup will be longer until the system stabilizes.
CU1526, CU2026, CU3030
Service Manual
Model
70 50
o
o
F air / F. water
90 70
o
o
F. air / F. water
CU1526A 22-25 36-29
CU1526W 21-24 28-31
CU2026A 15-18 25-28
CU2026W 15-18 20-23
CU3030A 12-15 19-22
CU3030W 10-13 15-18
Page 9
CU1526, CU2026, CU3030 Service Manual
Adjustments
Bridge Thickness - For the Service Tech Only
1. Remove left louver, locate controller on and off switches.
2. Push and hold Off till the machine stops.
3. Remove curtain.
4. Use a hex wrench and rotate the bridge thickness adjustment screw in 1/8 turn increments CW to increase bridge thickness. Rotate CCW to decrease bridge thickness.
1/8-3/16"
bridge
Caution: Do not make the bridge too thin or the machine will not harvest properly. Bridge thickness adjustments are not covered by warranty.
5. Return curtain and louver to their normal positions.
6. Push and release the On button. Check next harvest of ice. Repeat steps 1-6 if needed.
Water Purge Setting
The water purge is factory set to the automatic position, suitable for most water conditions. The setting can be changed to one of 5 manual settings or left on automatic.
Purge setting
Water Type
1 - Minimum
RO water or equivalent
2­Moderate
Low TDS non-RO water
3­Standard
Use for typical water
Too Big
Just Right
Too Small
Ice Bridge Thickness Measurement
Adjustment Screw
Bridge Thickness Adjustment Mechanism
4 - Heavy 5 - Maximum A - Automatic
Any with High TDS water
Very High TDS water
conductivity not
less than 10
microSiemens/cm
To set:
1. Switch the machine OFF by holding the Off button in until a number or the letter A shows on the display.
2. Press and release the On button repeatedly until the number on the display corresponds to the desired setting.
3. Press and release the Off switch again to return to the normal control state.
Page 10
Use and Operation
Manual Harvest
Clean
Code
Display
Component Operation Indicator Lights
Code Description
.... ......FreezeCycle
flashes....FreezeCycleisPending
.... ......HarvestCycle
flashes....Manual Harvest
.... ......BinisFull
.... ......Clean Cycle
.... ......BoardLocked
.... ......TestMode
.... ......Off
.... ......SelfTestFailed
flashes....MaxFreeze-Retrying
..... ......MaxFreezeTimeShutDown
flashes....MaxHarvest-Retrying
.... ......MaxHarvestTimeShutDown
.... ......SlowWaterFill
.... ......High Discharge Temp
.... ......SumpTempSensorFailure
.... ......DischargeTempSensorFailure
flashes...ShortFreeze-Retrying
Short Freeze - Thin ice
- Unit Remotely
Locked Out - Contact Leasing Company
F F H H b C L d O E 1 1 2 2 3 4 5 7 8
8............
All 4 Upper Lights Flashing
Control Operation - See Manual
Water Light On
De-Scale Light On
Flush Setting
TestMode
Recall Diagnostic Codes
Reset from Code 1, 2, 4 or 8
- Restore water supply to
machine.
- Clean and sanitize
machine.
- ToChange: Depress Off for 3 seconds. Press On to select purge (1-5) setting or Afor Automatic.
- Depress Off for 3 seconds,
then depress Clean for 3 seconds.
- Depress Off for 3 seconds. Press Harvest repeatedly to go from most recent to oldest of 10.
- Depress
Off then Depress On.
TechnicianSection
02-4302-01
On Off
Power
Status
De-scaleWater
Sanitize
Once started, the ice machine will automatically make ice until the bin is full of ice. When ice level drops, the ice machine will resume making ice.
There are four indicator lights at the front of the control box that provide information on the condition of the machine.
Indicator Lights:
Power
•
Status
•
Water
•
De-scale & Sanitize
•
Indicator Lights & Their Meanings
Power Status Water De-Scale & Sanitize
CU1526, CU2026, CU3030
Service Manual
Steady Green Normal Normal – bin full or making ice - -
Blinking Green
Blinking Red -
Yellow - - -
Blinking Yellow
Self Test Failure
Switching on or off - -
Diagnostic shutdown or, if making ice, temperature sensor failure
Lack of water
-
Time to de-scale and sanitize
- - - In Cleaning mode
Light off No power Switched off Normal Normal
All Blinking Unit remotely locked out – check with leasing company
If the Water light is on, the machine has sensed a lack of water. Check the water supply to the machine. The water could have been shut off or the water filter cartridges might need to be changed.
Note: Water cooled models, the refrigeration system discharge pressure is factory set at 245 PSIG, which should yield a freeze cycle discharge water temperature of about 105-110 degrees F.
If the De-Scale light is on, the machine has
Adjust if necessary.
determined that it needs to be cleaned. Contact an authorized Scotsman service agent and have the machine cleaned, de-scaled and sanitized.
Page 11
CU1526, CU2026, CU3030
Manual
Harvest
Clean
Code
Display
Component Operation Indicator Lights
Code Description
.... ......FreezeCycle
flashes....FreezeCycleisPending
.... ......HarvestCycle
flashes....Manual Harvest
.... ......BinisFull
.... ......Clean Cycle
.... ......BoardLocked
.... ......TestMode
.... ......Off
.... ......SelfTestFailed
flashes....MaxFreeze-Retrying
..... ......MaxFreezeTimeShutDown
flashes....MaxHarvest-Retrying
.... ......MaxHarvestTimeShutDown
.... ......SlowWaterFill
.... ......High Discharge Temp
.... ......SumpTempSensorFailure
.... ......DischargeTempSensorFailure
flashes ...ShortFreeze-Retrying
Short Freeze - Thin ice
- Unit Remotely
Locked Out - Contact Leasing Company
F F H H b C L d O E 1 1 2 2 3 4 5 7 8
8............
All 4 Upper Lights Flashing
Control Operation - See Manual
Water Light On
De-Scale Light On
Flush Setting
Test Mode
Recall Diagnostic Codes
Reset from Code 1, 2, 4 or 8
- Restore water supply to
machine.
- Clean and sanitize
machine.
- To Change: Depress Off for 3 seconds. Press On to select purge (1-5) setting or A forAutomatic.
- Depress Off for 3 seconds,
then depress Clean for 3 seconds.
- Depress Off for 3 seconds. Press Harvest repeatedly to go from most recent to oldest of 10.
- Depress
Off then Depress On.
Technician Section
02-4302-01
On Off
Power
Status
De-scaleWater
Sanitize
Service Manual
Control Switches
There is a front on and off switch, located in the top center of the louvers. Switching this switch Off will immediately stop the machine. Switching it back on will cause the machine to start in a timed harvest cycle.
The controller also has on and off switches, which can also switch the machine on and off, but their operation is different:
To switch the machine OFF, push and release the Off button. The machine will shut off at the end of the next cycle. To shut the machine off immediately, push and hold the Off button for 3 seconds.
To switch the machine ON, push and release the On button. The machine will go through a start up process and then resume ice making.
Note: Front On/Off Switch discontinued February 2012
Note: A Component Indicator Light switches ON to indicate that the component is operating.
Note: There are two Curtain Switch lights, SW1 and SW2. These single plate models have one curtain switch light on all the time, as a curtain switch light is ON when a curtain is either open or not present.
February 2012
Page 12
CU1526, CU2026, CU3030 Service Manual
Cuber System Information
Overall System Type:
Refrigeration: Mechanical, either air cooled or water cooled
•
Water System: Inlet water float valve fills reservoir continuously. Purge solenoid valve opens to
•
discharge some reservoir water once per cycle. Control System: Electronic
•
Harvest cycle sensor: Conductivity probe
•
Water full/empty sensor: Conductivity probe
•
Bin Control: Curtain Switch
•
Ice type: Unified
•
Harvest system: Hot gas defrost with mechanical assist
•
Electrical Components:
Compressor
•
Contactor
•
Water Pump
•
Purge or purge Valve
•
Fan Motor(s)
•
Fan motor pressure control
•
High pressure cut out
•
Harvest Assist Solenoid
•
•
Hot Gas Valve
•
Controller
•
Transformer – 12v AC for the controller only
•
Water Sensor
•
Ice Thickness Sensor
•
Curtain Switch
Page 13
CU1526, CU2026, CU3030 Service Manual
Controller Information
Machine Indicator Lights
Power
•
Status
•
Water
•
Clean
•
Code Display
Main codes - automatically displayed
F .......Freeze Cycle
F flashes....Freeze Cycle is Pending
H .......Harvest Cycle
H flashes . . . Manual Harvest
b .......BinisFull
C .......Clean Cycle
L .......Board Locked
d .......Test Mode
O .......Off
E .......Self Test Failed
1 flashes....MaxFreeze - Retrying
1 .......MaxFreeze Time Shut Down
2 flashes....MaxHarvest - Retrying
2 .......MaxHarvest Time Shut Down
3 .......Slow Water Fill
4 .......High Discharge Temp
5 .......Sump Temp Sensor Failure
7 .......Discharge Temp Sensor Failure
8 flashes....Short Freeze - Retrying
8 .......Short Freeze - Thin ice
Setting Codes - requires push button sequence for access
Water Purge Settings
A, 1, 2, 3, 4, 5
De-scale Interval Settings
6, 5, 4, 3
Page 14
CU1526, CU2026, CU3030 Service Manual
Controller Information
Component Indicator Lights
Condenser Fan / Aux
•
Water Pump
•
Purge Valve
•
Water Solenoid
•
Hot Gas
•
Compressor
•
Ready to Harvest
•
Sump Empty
•
Sump Full
•
Curtain SW1
•
Curtain SW2
•
Component Indicator Light Table
System Indicator Light ON
Condenser Fan / AUX Fan Motor Powered
Water Pump Pump Motor Powered
Purge Valve Purge Valve Opens
Inlet Water Solenoid Valve
Hot Gas Hot Gas Valve Opens and harvest assist solenoid powered
Compressor
Ready to Harvest Water contacting ice thickness sensor probe
Sump Empty Open between mid sensor and common
Sump Full
Curtain Switch Curtain open
Not used this model
Contactor Closes
Closed between top probe and mid probe
Page 15
CU1526, CU2026, CU3030 Service Manual
How It Works - Air Cooled
Freeze Cycle. At start up the controller operates the water pump and purge valve to drain the reservoir.
The float valve refills the reservoir after the purge valve shuts off. When the reservoir has filled, the compressor and water pump start. After the discharge pressure has increased past the cut in point of the fan pressure control, the fan motor(s) will begin to operate and warm air will be discharged. The fan motor will switch on and off as the discharge pressure rises and falls. Water flows over the evaporator as the refrigeration system begins to remove heat. When the water temperature falls to a preset point, as measured by the water temperature sensor, the controller shuts off the water pump for 30 seconds. The freeze cycle resumes when the pump restarts and ice begins to form on the evaporator. As it forms, the water flowing over the ice moves closer and closer to the metal tip of the ice thickness sensor. When it comes into contact with the sensor for a few continuous seconds, that signals the controller that the freeze cycle is complete.
The controller may shut the air cooled fan motor off for a variable period of time to build up heat for harvest. This is dependant upon the temperature of the discharge line sensor.
Harvest Cycle. When the harvest cycle begins, the controller shuts off the fan motor, switches on the hot gas valve, and through a parallel circuit, the harvest assist solenoid. After a few seconds the purge valve opens and water is drained from the reservoir. Based on either the automatic purge or manual purge setting, the pump and purge valve will be switched off at a time determined to have drained enough water for that setting. The float valve will open to fill the reservoir anytime during the reservoir drain cycle. Harvest continues as the hot discharge gas flows into the evaporator serpentine, heating up the evaporator. At the same time the harvest assist solenoid is pushing against the back of the ice slab. When the ice releases from the evaporator, it harvests as a unit, and the harvest assist probe provides some additional force to push it off. When the ice falls off it will force the curtain open. An open curtain during the harvest cycle signals the controller that the evaporator has released its ice, and the controller will terminate harvest. If the curtain remains open, the controller will shut the machine down on bin full. Anytime harvest is complete the hot gas valve and harvest assist solenoid are shut off. The harvest assist solenoid pin returns to its normal position by spring pressure.
If the curtain re-closes after harvest, the freeze cycle will restart.
September 2008
Page 16
CU1526, CU2026, CU3030 Service Manual
How It Works - Water Cooled
Freeze Cycle. At start up the controller operates the water pump and purge valve to drain the reservoir.
The float valve refills the reservoir after the purge valve shuts off. When the reservoir has filled, the compressor and water pump start. After the discharge pressure has increased past the set point of the water regulating valve, the water regulating valve will open and warm water will be discharged out the condenser drain. The water regulating valve will modulate to maintain a relatively constant discharge pressure. Water flows over the evaporator as the refrigeration system begins to remove heat. When the water temperature falls to a preset point, as measured by the water temperature sensor, the controller shuts off the water pump for 30 seconds. The freeze cycle resumes when the pump restarts and ice begins to form on the evaporator. As it forms, the water flowing over the ice moves closer and closer to the metal tip of the ice thickness sensor. When it comes into contact with the sensor for a few continuous seconds, that signals the controller that the freeze cycle is complete.
Harvest Cycle. When the harvest cycle begins, the controller switches on the hot gas valve, and through a parallel circuit, the harvest assist solenoid. After a few seconds the purge valve opens and water is drained from the reservoir. Based on either the automatic purge or manual purge setting, the pump and purge valve will be switched off at a time determined to have drained enough water for that setting. The inlet water float valve will open to fill the reservoir anytime during the reservoir drain cycle. Harvest continues as the hot discharge gas flows into the evaporator serpentine, heating up the evaporator. At the same time the harvest assist solenoid is pushing against the back of the ice slab. When the ice releases from the evaporator, it harvests as a unit, and the harvest assist probe provides some additional force to push it off. When the ice falls off it will force the curtain open. An open curtain during the harvest cycle signals the controller that the evaporator has released its ice and the controller will terminate harvest. If the curtain remains open, the controller will shut the machine down. Anytime harvest is complete the hot gas valve and harvest assist solenoid are shut off. The harvest assist solenoid pin returns to its normal position by spring pressure.
If the curtain re-closes after harvest, the freeze cycle will restart
Page 17
CU1526, CU2026, CU3030 Service Manual
Electrical Sequence - Air or Water Cooled
Power connected, unit previously switched Off.
Control board does a self check. If the self check fails, the unit displays an E and no further action will occur.
If the self check passes, the controller will display a 0, the curtain light(s) will be ON and the Power and Sump Empty lights will be ON.
Pushing and releasing the On button will start the ice making process.
The display will begin to blink F. The component indicator lights will switch on and off to match the following process:
The purge valve opens and the water pump starts to empty the reservoir. This is done to discharge
•
any excess water from ice melting into the reservoir. The hot gas valve and the harvest assist solenoid are energized.
•
The float valve will open to fill the reservoir. The water valve can open any time the water level is
•
low. After a few seconds the purge valve closes and the pump shuts off.
•
When the reservoir is full the compressor switches on. Five seconds after the compressor starts
•
the hot gas valve and the harvest assist solenoid are de-energized.
Light Information: The display shows a non-blinking F. The Power and Status Lights will be Green. The compressor, fan motor, water pump, sump full and one or two curtain switch lights will be ON.
The air cooled model's fan motor will start to turn when the discharge pressure has built up to the fan pressure control's cut in point. This is about 15 seconds after the compressor starts.
The Freeze cycle continues. The compressor, water pump, fan motor and curtain indicator lights will be ON. When the reservoir water temperature falls to a certain preset point, the water pump will shut off for 30 seconds. This is the anti-slush period. At this time the controller checks the conductivity of the water in the reservoir for the auto-purge feature. After the water pump restarts the Sump Full light will go out and neither sump lights will be on for the rest of the freeze cycle.
When the ice has built up enough so that the water flowing over the evaporator comes into continuous contact with the ice level sensor, the Ready to Harvest light will begin to blink on and off. When it has been On continuously for 5 seconds, the controller will switch the machine into a Harvest cycle.
Page 18
CU1526, CU2026, CU3030 Service Manual
Electrical Sequence - Air or Water Cooled (continued)
Indicator Information: The display shows a non-blinking H. The Power and Status Lights will be Green. The compressor, hot gas valve and one or two curtain switch lights will be ON. After a few seconds the water pump, purge valve and inlet water valve lights will come on.
The fan motor(s) shut off and remain off throughout the harvest cycle.
The harvest assist solenoid is connected in parallel with the hot gas valve. Although it is energized throughout the harvest cycle, its piston does not move until the ice has become partially loosened from the evaporator plate by the action of the hot refrigerant gas passing through the evaporator serpentine.
The water pump and purge valve will shut off when the purge level setting time has been reached, either the manual time or the automatic time. The inlet water valve will remain on until it fills the reservoir. The Ready to Harvest light will switch Off when the ice falls from the evaporator.
Harvest continues until the ice slab is ejected from the evaporator and falls, opening the curtain. When the curtain opens, the magnetic reed curtain switch opens, breaking the circuit to the controller. If the curtain re-closes within 30 seconds, the controller switches the machine back into another freeze cycle. If the curtain switch remains open, the controller shuts the machine down and puts it into a standby position.
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