Nor-Lake Plasma Freezers & Blood Bank Refrigerators - Manual (Page 8)

8
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
6. Air flow to condenser or 6. Remove obstruction for free airflow
evaporator blocked
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 rattles 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