TROUBLESHOOTING GUIDE
SYMPTOM | CAUSE | REMEDY | |
Compressor does not run Ð | Power off. | Restore power. | |
Contactor open |
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Fuses blown. | Replace with correct fuses after ®nding cause | ||
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| and correcting. | |
| Transformer open/shorted. | Replace transformer if primary windings are | |
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| receiving power and no output. | |
| Thermostat circuit open. | Check thermostat setting. | |
| Check for refrigerant undercharge or system | ||
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| leak. | |
| Check for refrigerant over charge or | ||
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| obstruction of outdoor air¯ow. | |
| Connections loose. | Tighten all connections. | |
| Compressor motor thermostat open. | Check for excessive motor temperature. | |
Compressor does not run Ð | Compressor leads loose, broken. | Check connections with power off. | |
Contactor closed |
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Single phasing. | Replace blown fuse. | ||
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| Compressor internal overload open. | Allow compressor motor windings to cool down to reset | |
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| overload. Determine cause for overload opening. | |
Compressor cycles on high- | Replace switch. | ||
pressure switch Ð |
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Air¯ow restricted. Dirty coil. | Remove obstruction, clean condenser coil. | ||
Condenser fan on | |||
Air recirculating. | Clear air¯ow area. | ||
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| Noncondensables in system. | Recover, evacuate and recharge as required. Refer to | |
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| Carrier | |
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| Recycling, and Reclamation. | |
| Refrigerant overcharge. | Recover as required. | |
| Refrigerant system restrictions. | Check or replace ®lter drier, expansion | |
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| valve, etc. | |
Compressor cycles on high- | Fan slips on shaft. | Tighten fan hub screws. | |
pressure switch Ð |
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Motor not running. | Check power and capacitor 1¤3 and 3¤4 hp motor. | ||
Condenser fan off |
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Motor bearings seized. | Replace motor. | ||
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| Motor overload open. | Check overload rating. Check for | |
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| fan blade obstruction. | |
| Motor burned out, windings open. | Replace motor. | |
Compressor cycles on low- | Filter drier plugged. | Replace ®lter drier. | |
pressure switch Ð |
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Expansion valve power head | Replace power head. | ||
Evaporator fan running | |||
defective. |
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| Low refrigerant charge. | Find leak, repair, evacuate system, and recharge. | |
| Expansion valve restricted/plugged. | Remove and replace expansion valve. | |
Air¯ow restricted Ð | Evaporator coil iced up. | Check refrigerant charge. | |
Low suction pressure |
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Evaporator coil dirty. | Clean coil ®ns. | ||
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| Clean or replace ®lters. | ||
| Check damper operation and position. | ||
Indoor (evaporator) fan stopped Ð | Electrical connections loose. | Tighten all connections. | |
Low suction pressure |
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Fan relay defective. | Replace relay. | ||
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| Motor overload open. | Check power supply. | |
| Motor defective. | Replace motor. | |
| Fan belt broken or slipping. | Replace or tighten belt. | |
Compressor runs but | Refrigerant charge low. | Add charge. | |
cooling insufficient Ð |
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Head pressure low. | Check refrigerant charge. | ||
Suction pressure low | |||
Clean or replace ®lters. | |||
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| Expansion valve power head | Replace power head. | |
| defective. |
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| Expansion valve restricted/plugged. | Remove and replace expansion valve. | |
| Evaporator coil partially iced. | Check | |
| Evaporator air¯ow restricted. | Remove obstruction. | |
Compressor runs but | Heat load excessive. | Check for open doors or windows. | |
cooling insufficient Ð |
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Suction pressure high |
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NOTE: See Fig. 16 and 17 for component arrangements.