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26
WORKTOPS/UNDERCOUNTERS & SANDWICH UNITS
OPERATIONS MANUAL
PROBLEM PROBABLE CAUSE CORRECTION
Condensing unit will not
start - no hum.
1. Line disconnected, switch open.
2. Fuse removed or blown.
3. Overload protector blown.
4. Control “Off” due to cold location.
5. Control stuck in open position.
6. Wiring improper or loose.
1. Close start or disconnect switch.
2. Replace Fuse.
3. Determine reason and correct/replace.
4. Relocate control.
5. Repair or replace control.
6. Check wiring against diagram.
Condensing unit will not
start - hums but trips on
overload protector.
1. Improperly wired.
2. Low voltage to unit.
3. Starting capacitor defective.
4. Relay failing to close.
5. Compressor motor has a shorted or open
winding.
6. Internal mechanical trouble in compressor.
7. Insufcient air supply.
1. Check wiring against diagram.
2. Determine reason and correct.
3. Determine reason and replace.
4. Determine reason and replace.
5. Replace compressor.
6. Replace compressor.
7. Clear condenser and allow compressor
to cool down.
Condensing unit starts
and runs, but short
cycles on overload
protector.
1. Additional current passing through overload
protector.
2. Low voltage unit.
3. Overload protector defective.
4. Run capacitor defective.
5. Excessive discharge pressure.
6. Excessive suction pressure.
7. Insufcient air supply.
1. Check wire diagram. Check for added
components connected to wrong side of
overload protector.
2. Determine reason and correct.
3. Check current, replace protector.
4. Determine reason and replace.
5. Check ventilation, restrictions in cooling
medium or refrig. system.
6. Check for misapplication.
7. Clear condenser and allow compressor
to cool down.
Condensing unit starts,
but fails to switch off of
“start” winding.
1. Improperly wired.
2. Low voltage to unit.
3. Relay failing to open.
4. Run capacitor defective.
5. Excessively high discharge pressure.
6. Compressor motor has a shorted or open
winding.
7. Internal mechanical trouble in compressor.
1. Check wiring against diagram.
2. Determine reason and correct.
3. Determine reason and replace.
4. Determine reason and replace.
5. Check discharge shut-off valve, possible
overcharge.
6. Replace compressor.
7. Replace compressor.
Condensing unit runs,
but short cycles on:
1. Overload protector.
2. Thermostat.
3. High pressure cut-out due to:
(a) Insufcient air supply.
(b) Overcharge.
(c) Air in system.
4. Low pressure cut-out due to:
(a) Valve leak.
(b) Undercharge.
(c) Restriction in expansion device.
1. See Problem 3
2. Differential must be widened.
3.
(a) Check air supply to condenser.
(b) Evacuate and re-charge.
(c) Evacuate and re-charge.
4.
(a) Replace, evecuate and re-charge.
(b) Evacuate and re-charge.
(c) Replace expansion device.
Condensing unit runs,
but for prolonged peri-
ods or continuous.
1. Shortage of refrigerant.
2. Control contacts stuck closed.
3. Excessive heat load placed into cabinet.
4. Prolonged or too frequent door openings.
5. Evaporator coil iced.
6. Restriction in refrigeration system.
7. Dirty condenser.
8. Filter drier clogged.
1. Fix leak, evacuate and re-charge.
2. Clean contacts or replace control.
3. Allow unit sufcient time for removal of latent
heat.
4. Plan or organize schedule to correct condition.
5. Defrost evaporator coil.
6. Determine location and remove.
7. Clean condenser coil.
8. Replace, evacuate and re-charge.
TROUBLESHOOTING GUIDE
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