SUB-ZERO 506 Component Access and Removal UC Ice Maker

Specifications

• Model: 506 (UC Ice Maker)
• Revision: B
• Year: May 2006

Control Panel Removal:

1. Remove the control knobs from the control panel.
2. Remove the crews located on the underside of the panel at each end.
3. Pull the escutcheon off the unit.
4. If present, remove wire leads to the door switch.
5. Extract the screws securing the control panel to the cabinet.
6. Carefully pull the control panel down and tilt outward.
7. Disconnect wire leads from component terminals to remove control panel components.

Control Panel Component Testing:
The service control switch is a manually operated three-position rotary switch. To test:

1. Remove wire leads.
2. Use an ohmmeter set on the R x 1 scale.
3. Check across terminals with the switch in different positions (ON, CLEAN).

Evaporator Thermostat Testing:
To test the evaporator thermostat, follow method 1 or method 2 as described in the manual.

Bin Thermostat Replacement:
When replacing the bin thermostat, ensure to make necessary bends in the capillary tubing for proper installation.

Component Access & Removal Model 506 (UC Ice Maker)Model 506 (UC Ice Maker)

COMPONENT ACCESS AND REMOVAL

This section explains how to access and remove components in a Model 506 under-counter ice maker.

This section is arranged as follows: Exterior components,s; followed by the internal components, followed by compressor area components. An attempt has been made to arrange these procedures in such a way as to simulate which components would need to be removed first to gain access to other components. When following a component removal procedure, it may be necessary to reference another component removal procedure listed earlier in this section.

NOTE: Before continuing, please take note of the WARNINGS and CAUTIONS below.

WARNING
TO AVOID ELECTRIC SHOCK, POWER TO THE UNIT MUST BE DISCONNECTED WHENEVER ACCESSING AND/OR REMOVING COMPONENTS POWERED BY ELECTRICITY OR COMPONENTS NEAR OTHER ELECTRICAL COMPONENTS.

CAUTION

• If removing or disconnecting door hinge assemblies, remember they are spring-loaded and may recoil quickly when released.
• If working in the compressor area, remember that the compressor and tubing may be hot.
• If working on or around the condenser, remember that condenser fins are sharp.

Control Panel

The service control switch, evaporator thermostat control, bin thermostat control, and the transformer are located behind the control panel. They are all secured to the control panel with screws that pass through the front of the control panel. To remove the control panel:

1. Remove the control knobs from the control panel.
2. At each end of the control panel, remove the screws located on the underside of the panel. (See Figure 4-1)
3. Pull the escutcheon off of unit.
4. If present, remove the wire leads to the door switch.
5. Extract the screws that secure the control panel to the cabinet
6. Carefully pull the control panel down and tilt outward.
7. Remove control panel components by first disconnecting leads from component terminals. (See Figure 4-2)
8. Extract screws that pass through the front face of the control panel and fasten into the component being removed.

Control Panel Component Testing
Service Control Switch

NOTE: See the WARNING at the beginning of this section.
The service control switch is a manually operated three-position rotary switch.

To test:

1. Remove wire leads.
2. Use an ohmmeter set on the R x 1 scale.
3. With the switch in the “ON” position, check across terminals (See Figure 4-3)
4. With the itch in the “CLEAN” position, check across terminals.

Evaporator Thermostat

The evaporator thermostat is adjustable for altitude correction. In the warm position, the thermostat cuts in at 38°F ± 2° and cuts out at 10.5°F ± 4°FF. In the cold posi-tion, the thermostat cuts in at 38°F± 2°, and cuts out at -3°F± 2.5°
To test, method 1:

1. Remove wire leads.
2. Use an ohmmeter set on the R x 1 scale.
3. Feel the evaporator freezing plate. Then check across the terminals. (See Figure 4-4)
   1. If the evaporator is cold:
   2. If the evaporator is warm:

To test, method 2:

1. Remove the wire lead from terminal 6 on the service control switch (disabling the water pump). (See Figure 4-5)
2. Reassemble the unit.
3. Reconnect the power supply to the unit.
4. Turn the control service switch to the ”ON” position.
5. Feel the evaporator plate. It should first get cold, then warm.

With the load removed from the evaporator, the evaporator thermostat should cycle into the HARVEST cycle within a matter of minutes.

Bin Thermostat
The bin thermostat operates automatically and is adjustable for altitude correction. The bin thermostat cuts in at 41°F R1.5, nd cuts out at 35°F R1.5.

The control capillary bulb thermostat is located in a well on the left side of the bin liner.

If the bin thermostat is replaced, it is necessary to carefully make a few bends in the capillary tubing before it is threaded into the well, to make certain that the capillary touches the inside wall of the well.

To test:

1. Remove the wire leads.
2. Use an ohmmeter set on the R x 1 scale.
3. Check between terminals. (See Figure 4-6)

• When the thermostat well is warm, the terminals should read on the ohmmeter as a closed circuit.
• When the thermostat well is cold (hold ice against the well), the terminals should read on the ohmmeter as an open circuit.

Transformer

The transformer has a 115-volt, AC primary coil, with a secondary coil that produces 8.5 Volts at 2 Amps.

A special replacement service transformer is available from your FSP parts distributor with a selectable 11-volt tap. This higher voltage will slightly increase the heat of the cutter grid wires. If the water supply to the ice maker has a high mineral content, the ice will have a higher melting temperature. The warmer grid wires will help divide the ice slab into cubes faster.

To test:

1. Remove the wire leads. (See Figure 4-7)
2. Attach a 120-volt test cord to the primary coil.
3. Use a voltmeter to test across the terminals of the secondary coil. The meter should indicate 8.5 volts AC.

Door Light Switch
If present on the unit, the switch is located on the bottom left of the escutcheon.

To test:

1.  Remove the wire leads.
2. Use an ohmmeter set on the R x 1 scale.
3. Test across the terminals. The ohmmeter should indicate a closed circuit.
   Then, depress the switch and test. The ohmmeter should indicate an open circuit.

Bin Area Components

Bin Door
To remove the bin door:

1. Open the door and snap out the ice retainer by flexing it and slipping it off the retaining studs. (See Figure 4-8)
2. Remove the screw closest to the door hinge on either the right side or the left side of the door. (See Figure 4- 9)
3. Remove the soft white plastic filler plug covering the door hinge pin on the side where the screw was removed.
4. Spread the trim piece free from the door.
5. Press down on the inside of the door liner next to the hinge, while pulling the door up and off the hinge pin.
6. Close the door to a 30-degree open position, and slide the door off the hinge pin on the other side.

Friction Door Catch
The catch is located on the bottom of the escutcheon. It can often be adjusted by adding washers under the catch. If these do not correct the problem, the catch should be replaced.

Cutter Grid

NOTE: See the WARNING at the beginning of this section.

• The cutter grid is an arrangement of Incoloy wires supported by a four-sided frame in a manner to forms squares. There are two cutter grids available. (See Figure 4-10)
• The cube cutter grid has wires that produce ice cubes that are 1-1/4 inches by 1-1/4 inches. The wires are arranged in a single circuit.
• The cubelet cutter grid has wires that produce ice cubelets that are 3/4 inch by 3/4 inch. The wires are arranged in two parallel circuits.

Cutter Grid (Continued)

To remove and check:
Before removing the grid, while the unit is operating, feel the grid wires. They should feel warm to the touch.

1. Remove the thumb screws that are in front of the cutter grid assembly. (See Figure 4-11)
2. Carefully pull the cutter grid out.
3. Unplug the cutter grid from the unit’s wiring harness.
4. Visually check the wiring plug. It should be free of mineral buildup. The plastic plug should not show any sign of melting. (Excessive mineral build-up on the plug terminals can cause the plug to overheat.)
5. Visually check the grid wires. They should be taut and free of mineral buildup. They should not have black spots where the wires have sagged and touched each other. If wires are bad, the entire circuit grid should be replaced.
6. Visually check the terminals, insulators,, and frame. They should all be free of minerabuildupp. The insulators should not show any signs of melting.
   If the terminals, insulators, or frame are bad, the entire cutter grid should be replaced.

Bin Light

• If present, the bin light will be located on the cutter grid assembly.
• To replace the light bulb, it is necessary to remove the cutter grid assembly and the plastic light shield. (See Figure 4-12)

Water Reservoir Pan
The reservoir pan is a plastic tub with a drain hole and an overflow boss to which a drain tube is mounted. The pan is located under the evaporator toward the rear of the inside ofthe  the bin.

To remove (See Figure 4-13):

1. Though not necessary, it is recommended that the bin door be removed for easier access.
2. Remove thumbscrews at the top of the reservoir pan.
3. Pull out the reservoir pan and check for mineral build-up, slime, or mildew.

• A water inlet tube runs into the reservoir pan from the water inlet valve in the unit compartment. The tube must be secured in its slot on the water pump bracket.
• A plastic drain tube runs from the overflow boss, or standpipe, on the reservoir pan down through the bin drain.

Water Pump
The water pump is mounted on a bracket on the back of the bin and sits in the water pan. The water pump is supplied with an internal overload protector and rotates at 3350 RPM. (See Figure 4-14)

To remove:

1. Though not necessary, it is recommended that the bin door be removed for easier access.
2. Remove the water reservoir pan.
3. Remove the screws that secure the pump to the mounting bracket on the back bin wall.
4. Snap out the water inlet tube from the notch on the water pump bracket.
5. Remove the water pump outlet tube.
6. Pull the pump forward, out of the socket on the rear bin wall.

To test:

1. Attach a 120-volt test cord to the water pump plug (the top two pins). The pump should operate when power is supplied.
2. Visually check the water pump plug and the socket on the rear bin wall. They should both be free of mineral buildup and any signs of overheating.
3. Check the agitator arm on the bottom of the water pump. ItThis arm mustn’t bero-ken off while removing or replacing the pump.
   The agitator arm breaks up bubbles in the water and prevents an airlock from forming in the impeller area of the pump.
   If the agitator arm is broken off, water may be prevented from being pumped up to the distributor. An improperly operating agitator can also cause other ice-making problems and low-quality ice.
   If there are any problems with the pump impeller or agitator, the entire water pump should be replaced.

Evaporator

• The evaporator freezing plate is located directly behind the cutter grid assembly.
• The evaporator thermostat capillary bulb is attached to the underside of the evaporator plate. At least 8 inches of the thermostat capillary bulb must be bent into an ‘M* shape and attached tightly against the bracket on the bottom side of the evaporator plate.
• The capillary tube of the refrigeration sealed system
  is soldered directly against the front edge of the evaporator plate. This prevents the ice slab from forming a lip over the edge.
• At least one inch of the thermostat capillary bulb should be taped to the refrigeration system capillary tube at the front edge of the evaporator plate. This helps to shorten the HARVEST cycle.
• The upper surface side flanges of the evaporator freezing plate must be free of mineral build-up and be smooth and even. A nick or scratch could cause the ice slab to hang up during the HARVEST cycle.
• If evthe aporator plate is cleaned with a plastic scrubber, always scrub in the direction of water flow (front to back). If the plate is scratched during cleaning, it will not hinder the ice slab from sliding off. The evaporator plate can be dropped for better access.
• To drop:
  1. Though not necessary, it is recommended that the bin door be removed for easier access.
  2. Remove the cutter grid assembly, water reservoir pan, and water pump.
  3. Remove the thumb screws on the side brackets at the front of the evaporator plate.
  4. Carefully pull the evaporator forward and down. Be careful not to bend or kink the attached tubing. The evaporator can be pulled forward to the front of the bin area, where the unit compartment is pulled forward.

NOTE: If a component in the refrigeration sealing system must be replaced, it is necessary to use an approved method of accessing the sealed system.
Refer to the Job Aids below to provide information to determine whether other system components in the sealed system need replacing and to provide the approved method of accessing, servicing, and recharging the sealed system. Refrigerant recovery is also covered.

• 4321717 Sweep Charge Procedure for the 90’s.
• 4378421 Refrigerant Recovery Process.

WARNING
ALL AUTHORIZED SERVICERS MUST UTILIZE A CFC RECOVERY AND HANDLING PROGRAM THAT MEETS ALL THE REQUIREMENTS OF LOCAL, STATE, AND FEDERAL LAWS AND REGULATIONS

Side Brackets

• Plastic side brackets are attached to the front of each side of the evaporator freezing plate with thumb screws.(See Figure 4-15)
• The brackets support the cutter grid, the water reservoir, and the evaporator.

Distributor
The water distributor is a 5/8” diameter molded plastic tube with small holes,  and rubber caps inatach end. It distributes water evenly over the entire evaporator plate surface. (See Figure 4-16)

To remove:

1. Though not necessary, it is recommended that the bin door be removed for easier access.
2. Remove the cutter grid assembly, water reservoir pan, and water pump.
3. Drop the evaporator.
4. Disconnect the water tube that came from the water pump.
5. Pull the distributor out.

• The rubber end raps can be removed, and the distributor or cleaned with a small brush and a mild detergent solution. Each of the small holes in the distributor must be unrestricted.
• There is a built-in water restrictor at the inlet end of the distributor. The restrictor controls the amount of water running over the evaporator. The restrictor cannot be plugged.
• If a distributor is replaced, it is very important to use the proper size distributor. If the wrong size distributor is installed in an ice maker, water may flow over into the bin area.
• When replacing the distributor, note that the small stubs on the outside of the rubber end caps fit into notches on the rear of the side flanges of the evaporator plate. Also, there are small plastic nubs along the back side of the distributor. After the distributor is installed onto the rear of the evaporator plate, it should be turned downward until these nubs are tight against the back of the evaporator.

Components in the Unit Compartment

Accessing the Unit Compartment
The water inlet valve, the hot gas valve, the compressor (and starting relay and overload protectors), the condenser, the condenser accumulating tube, the condenser fan, anthe d dryer are located in the unit compartment.

To access the unit compartment:

1. Remove the two (2) screws at the bottom of the grille. (See Figure 4-17)
2. Pull the lower panel and grille assembly down and outward, releasing it from the two clips at the top.

There is a baffle separating the unit compartment. During operation of the unit, the air is pulled in through the lower grille on the right side of the baffle, across the condenser, and is pushed out through the lower grille on the left side of the baffle.

To remove the baffle:

1. Remove the screws on the compressor side that secure the baffle in place, and carefully remove it.
   It is always important that the baffle is replaced properly. If the baffle is not in place during operation, warm air could be continually recirculated through the unit area, resulting in inefficient operation and low-quality ice.

To pull out the unit compartment:

1. Remove the door, the cutter grid assembly, the water reservoir pan, the water pump, the lower panel and grille assembly, and the baffle.
2. Drop the evaporator.
3. Remove the screws that secure the shell front, and pull out the shell front.
4. Remove wire leads from the hot gas valve, the water inlet valve, and the compressor starting components.
5. Remove the inlet and outlet water tubes from the water inlet valve.
6. Loosen the bolts on the side rails at the bottom of the unit compartment.
7. Snap out the retaining spring clips along the left side of the front bin seal.
8. Carefully pull out the unit compartment several inches. Be careful to guide the sealed system tubing forward, through the left side of the bin, and the slit in the upper left front corner of the bin. Also, carefully guide the evaporator forward.
9. Remove the wire leads from the compressor fan when they become accessible while the unit compartment is being pulled out.
10. Pull the unit compartment out as far as it will come.

Condenser Fan
The condenser fan has a 3-watt motor that turns the fan blade at 1200 RPM. When facing the motor shaft, the fan blade will turn counterclockwise. To check or remove the condenser fan, the unit compartment will need to be pulled out of the unit.

To check:

1. After removing the wire leads, use an ohmmeter set on the R x 1 scale.
2. Check across terminals. The ohmmeter should read approximately 75 ohms.

The motor can also be checked by attaching a 120-volt test cord to the terminals. When power is supplied, the fan should operate.

To remove:

1. Remove the screws that secure the fan bracket to the base of the unit compartment. (See Figure 4-19)
2. Pull out the fan and bracket.
3. Remove the screws that secure the fan to the fan bracket.

Water Inlet Valve
The water inlet valve is located in the front of the unit compartment. The valve features a spring-loaded solenoid and has an 80-mesh screen in the water inlet.

To check:

1. After removing the wire leads, use an ohmmeter set on the R x 100 scale.
2. Test across the terminals. The ohmmeter should read approximately 250 ohms.

A flow washer in the water inlet valve controls water flow to approximately 1 quart of water per minute at a supply pressure of between 20 and 120 pounds psi.

To check for proper water flow:

1. Reconnect the water supply tube to the inlet side of the water valve.
2. Attach a tube to the outlet side of the water valve. Place the other end of the tube in a quart jar held over a pan to catch any overflow.
3. Attach a 120-volt test cord to the terminals.
4. Supply power to the water valve for 1 minute. During this time, one quart of water should flow into the jar. If not, check the wire mesh and flow washer for obstruction, then disassemble the water valve. (See Figure 4-21)

NOTE: When reassembling the flow washer, note that the side of the washer with lettering must face away from the body of the valve.

Compressor and Starting Components

Starting Relay
The starting relay is a magnetic current type that plugs directly onto the compressor terminals. The unit compartment will need to be pulled out to access the compressor and add the starting components. (See Figure 4-22)

To test:

1. Remove the relay from the compressor.
2. Use an ohmmeter set on the R x 1 scale. With the relay held upright in the same position as it was mounted on the compressor, place the meter probes into the R and S terminal sockets. The ohmmeter should read an open circuit.
3. With the meter probes still in the R and S terminal sockets, invert the relay. The ohmmeter should read a closed circuit.

Compressor Overload Protector
The compressor overload protector is mounted with the starting relay and is sensitive to the current load and the compressor temperature.

To test:

1. With the relay removed from the compressor, use an ohmmeter set on the R x 1 scale.
2. Check across the overload terminals. The ohmmeter should show an open circuit.

Compressor

To test:

1. Remove the starting components.
2. Use an ohmmeter set on the R x 10K scale. Check from each terminal (C,  S,  and R) to the compressor housing. The meter probe on the compressor housing should be placed on the grounding blade or in an area that is free of paint, such as a stub.
3. Set the meter on the R x 1 scale. Test across terminals R and C. The ohmmeter should read approximately 2.5 ohms.
4. Test across terminals C and S. The ohmmeter should read approximately 2.5 ohms.
5. Attach a 120-volt test cord to the compressor as shown. (See Figure 4-24)

If the compressor does not start, but an audible hum is heard, replace the compressor.

If the compressor starts with the test cord but refuses to run when the icemaker is operating, check for loose wiring, a defective relay, or a defective bin thermostat.

To remove (See Figure 4-23):

1. Before removing the compressor, capture the refrigerant in the sealed system.
2. Remove the terminal cover from the side of the compressor.
3. Disconnect electrical leads from overload/ relay assembly.
4. With a tube cutter, cut suction and discharge lines approximately one inch from compressor ports.
5. Extract screws from the corners of the compressor, and remove the compressor from the unit.

Condenser
The condenser is attached to the base assembly with screws that pass through the condenser base and are then secured to the unit area base. The condenser fan shroud is attached to the back of the condenser with screws passing through the shroud into the rear side flanges of the condenser. The inlet port of the condenser is attached to the compressor discharge line. The condenser outlet leads to the high-side filter-drier.

To access the condenser, pull out the unit compartment to access the sealed system components.

1. Extract the screws securing the front deflector to the side of the condenser.
2. Extract the screws securing the fan shroud to the back of the condenser.
3. Before removing the condenser, capture the refrigerant from the sealed system.
4. Then, cut the compressor discharge line and dryer inlet line approximately one inch from the condenser inlet and outlet ports.
5. Lift the condenser off the base assembly. (See Figure 4-24)

NOTE: It is not recommended to sweat tubing apart. Doing so will induce moisture into the sealed system.

Hot Gas Valve

• The hot gas valve must be installed vertically as the valve uses a free plunger that seats by gravity. This plunger must seat properly for efficient operation of the ice maker. (See Figure 4-25)
• If there is a small leak in the valve, the outlet tube from the valve will feel coldand may frost up, ring the ICE MAKING cycle. This is caused by the small leak acting as an orifice for the refrigerant gas.
• If there is a medium-sized leak in the valve, the outlet tube from the valve will feel warm during the ice-making cycle.
• If the outlet tube from the valve is hot during the ice-making cycle, the hot gas valve is stuck open.

To check:

1. With wire leads removed, use an ohmmeter set on the R x 100 scale.
2. Check across terminals. The ohmmeter should read approximately 250 ohms.
3. Attach a 120-volt test cord to the terminals. When power is supplied to the valve, an audible click should be heard.

To remove:

1. Before removing the hot gas valve, capture refrigerant from the sealed system.
2. Disconnect the coil harness from the olenoid.
3. Extract the crew from the top of the solenoid.
4. With a file, score a line around capillary tubes 1” or less from valve inlet and outlet tubes, then fatigue capillary tubes at these lines until they separate.

• NOTE: Whenever servicing the sealed system, the filter-drier must be replaced.
• NOTE: After the capillary tube separates, check the tubing for internal burrs. If burrs exist, repeat step 1 above.

FAQS

Q: How do I ensure safety when accessing components?
A: To avoid electric shock, always disconnect power to the unit before accessing or removing components powered by electricity or near other electrical components.

Documents / Resources

SUB-ZERO 506 Component Access and Removal UC Ice Maker [pdf] Instruction Manual 506 Component Access and Removal UC Ice Maker, 506, Component Access and Removal UC Ice Maker, Access and Removal UC Ice Maker, Removal UC Ice Maker, UC Ice Maker, Ice Maker, Maker

References

• User Manual