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6/21 Rev. E 171375
15
maintenance analysis
MALFUNCTION POSSIBLE CAUSE SOLUTION
Compressor will not start - 1. Unplugged or power off 1. Plug in service cord or turn power on
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 — warm ambient 4. Check refrigerant charge, fix leak if
conditions necessary
Compressor operates long 1. Short of refrigerant 1. Fix leak, add charge
or continuously 2. Control contact stuck 2. Repair or replace
3. Evaporator coil iced 3. Determine cause, defrost manually
4. Restriction in refrigeration system 4. Determine location and remove restriction
5. Dirty condenser —warm ambient 5. Clean condenser
conditions
6. Warm ambient 6. Address ambient conditions
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
6. Air flow to condenser or 6. Remove obstruction for free air flow — no storage
evaporator blocked on top of walk-in
7. Warm ambient conditions 7. Ambient conditions should be 90° or less
Standard temperature system 1. Control setting is too low 1. Reset the control
freezes the product
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
Water overflowing from 1. Air leak between refrigeration system 1. Check that refrigeration system is properly set
evaporator drain pan or and walk-in panel. in panel opening.
condensate vaporizer pan 2. Drain line from evaporator drain 2. Clean blockage from inside of drain line.
pan to condensate vaporizer is
blocked with foreign material.
3. Drain line from evaporator drain 3. Check that drain line heater (on freezers)
pan to condensate vaporizer is is working and repair or replace as required.
blocked with ice.
4. Walk-in operating in high humidity 4. Plumb drain line from evaporator to floor
environment (heavy door usage). drain or replace high gas vaporizer with
electric vaporizer. Consult factory for further information.
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