Master-Bilt MRR152 Owner’s Manual

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REFRIGERATED

PREPARATION TABLES

Installation, Operation and

Maintenance Instructions

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INSPECTION

When the equipment is received, all items should be carefully checked against the bill of lading to
insure all crates and cartons have been received. All units should be inspected for concealed
damage by uncrating the units immediately. If any damage is found, it should be reported to the
carrier at once, and a claim should be filed with the carrier. This equipment has been inspected and
tested in the Manufacturing Facility and has been crated in accordance with transportation rules
and guidelines. Manufacturer is not responsible for freight loss or damage.

INSTALLATION

GENERAL

After the unit crate and base have been removed, locate the legs or casters found in the interior of
the cabinet. Attach the legs or casters to the unit base by screwing them into the same threaded
fittings that were used to secure the crate base to the cabinet. Insure that they are screwed all the
way into the base.

LOCATION

The refrigeration system located at the bottom of the cabinet requires free air access for proper
operation. The cabinet may be enclosed on three sides, however, there must be a minimum four­inch clearance from the bottom of the cabinet to the floor. This model cannot be operated without
the legs or casters in place, and the bottom of the cabinet cannot be enclosed. The cabinet should
be level when it is placed in its permanent location.

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ELECTRICAL

Check the proposed outlet to be used to insure that the voltage, phase, and current carrying
capacity of the circuit from the electrical panel correspond to the requirements of the cabinet.
NEVER use an extension cord to wire any unit. All inter wiring between the electrical panel and the
unit must be done in accordance with the National Electric Code and all state and local codes.
Refer to the Electrical Data below and the Serial Tag for all pertinent electrical information.

Observe all Warning Labels. Disconnect power supply to eliminate injury from electrical
shock or moving parts when servicing equipment.

GENERAL OPERATION

The refrigerated Preparation Tables employ a unit cooler evaporator located inside the cabinet as
the heat-removing source. Through the refrigeration process, heat is captured in the evaporator,
transferred to the condensing unit located at the bottom of the cabinet, and expelled to the
surrounding outside air. It is extremely important to maintain the minimum four-inch clearance from
the bottom of the cabinet to the floor for the refrigeration process to function properly. The cabinet
cannot be operated without the legs or casters installed.

During the operation of these units, frost will periodically form on the coil surface. Each time the
refrigeration compressor cycles to the "off" position, the evaporator fans and condenser fans will
continue to run. This will tend to keep the interior of the cabinet at a constant temperature and at
the same time remove any frost build up on the unit by circulating the inside air over the coil. The
water produced will collect in the unit cooler drain pan and travel down a drain tube to the
condenser drain pan where the water will vaporize back into the air.

The refrigeration system is designed to provide a 38°F temperature. The system employs a
"constant cut-in" control. This device accomplishes control of the interior temperature by sensing
the evaporator coil. Since the control features a non-adjustable "cut-in" temperature of 38°F, and
the sensor tube is embedded in the fins of the evaporator coil, nuisance coil icing is eliminated
because the controller will not permit compressor start up until the coil reaches 38°F. Adjusting the
control knob on this system will adjust the "cut-out" temperature only. The control knob on the
refrigerator is located on the unit cooler front panel.

PAN AREA
The switch for the pan area is located on the front edge of the cabinet top. This switch controls

the pan area only and should be in the "OFF" position when the pan area is not in use. The
temperature control for the pan area is located adjacent to the switch and is factory set. It is

designed to maintain product temperature between 33°F and 41°F with ambient conditions between
70°F and 86°F. Should adjustment be necessary, carefully remove the plug button with a
screwdriver. Adjustment of the control can be made with a screwdriver by turning it no more than
1/2 setting on the scale, i.e. from 4 to 4-1/2. Allow the pan area one day to respond to the control
adjustment.

Product should not be stored in the pan area overnight. Product may freeze if left in the pan area for
more than four hours or if lids are closed.

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GENERAL MAINTENANCE

PERIODIC CLEANING

Beginning with the initial installation, the interior surfaces of the cabinet should be periodically
wiped down with a solution of warm water and baking soda. This solution will remove any odors
from spillage that has occurred. The exterior of the cabinet should also be cleaned frequently with a
commercial grade of glass cleaner.

Monthly cleaning of the condenser will aid the heat transfer characteristics of the refrigeration
system and increase its efficiency. To accomplish this, remove the cover panel from the cabinet and
use a wire brush to loosen any dirt particles that are attached to the fins. Use a vacuum cleaner to
remove the loosened particles. Failure to keep the condenser coil clean and clear of

obstructions could result in temperature loss and damage to the compressor.
The pan area is to be turned off as needed to manually defrost. After the pan area is turned off

it should be wiped dry using a soft rag.
All moving parts have been permanently lubricated and will generally require no maintenance.

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MAINTENANCE SERVICE AND ANALYSIS GUIDE

REFRIGERATION SYSTEMS - ALL MODELS

MALFUNCTION POSSIBLE CAUSE SOLUTION

Compressor will not start - 1. Service cord unplugged 1. Plug in service cord
no hum 2. Fuse blown or removed 2. Replace fuse

3. Overload tripped 3. Determine reasons and correct

4. Control stuck open 4. Repair or replace

5. Wiring incorrect 5. Check wiring against the diagram
Compressor will not start - 1. Improperly wired 1. Check wiring against the diagram

hums but trips on overload 2. Low voltage to unit 2. Determine reason and correct
protector 3. Starting capacitor defective 3. Determine reason and replace

4. Relay failing to close 4. Determine reason, correct or replace
Compressor starts and runs, 1. Low voltage to unit 1. Determine reason and correct

but short cycles on overload 2. Overload defective 2. Check current, replace overload protector
protector 3. Excessive head pressure 3. Check ventilation or restriction in
refrigeration system

4. Compressor hot-return gas hot 4. Check refrigerant charge, fix leak if necessary
Compressor operates long 1. Short of refrigerant 1. Fix leak, add refrigerant

or continuously 2. Control contact stuck 2. Repair or replace

3. Evaporator coil iced 3. Determine cause, defrost manually

4. Restriction in refrigeration 4. Determine location and remove restriction
system

5. Dirty condenser 5. Clean condenser
Compressor runs fine, but 1. Overload protector 1. Check wiring diagram

short cycles 2. Cold control 2. Differential too close - widen

3. Overcharge 3. Reduce charge

4. Air in system 4. Purge and recharge

5. Undercharge 5. Fix leak, add refrigerant
Starting capacitor open, 1. Relay contacts stuck 1. Clean contacts or replace relay

shorted or blown 2. Low voltage to unit 2. Determine reason and correct

3. Improper relay 3. Replace
Relay defective or burned out 1. Incorrect relay 1. Check and replace

2. Voltage too high or too low 2. Determine reason and correct
Refrigerated space too warm 1. Control setting too high 1. Reset control

2. Refrigerant overcharge 2. Purge refrigerant

3. Dirty condenser 3. Clean condenser

4. Evaporator coil iced 4. Determine reason and defrost

5. Not operating 5. Determine reason, replace if necessary
Standard temperature system 1. Control setting is too low 1. Reset the control

freezes the product 2. Control points stuck 2. Replace the control
Objectionable noise 1. Fan blade hitting fan shroud 1. Reform or cut away small section of shroud

2. Tubing rattle 2. Locate and reform

3. Vibrating fan blade 3. Replace fan blade

4. Condenser fan motor rattles 4. Check motor bracket mounting, tighten

5. General vibration 5. Compressor suspension bolts not loosened
on applicable models - loosen them

6. Worn fan motor bearings 6. Replace fan motor
Pan Area 1. No cooling 1. Make sure switch is in the "on" position

2. Too cold 2. Adjust temperature control - see instructions
under pan area

3. Too warm 3. Adjust temperature control - see instructions
under pan area

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