TROUBLESHOOTING AND DIAGNOSTICS (cont)
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COMPRESSOR RUNNING BUT COOLING INSUFFICIENT |
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| Suction Pressure Low |
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| 1. | Refrigerant charge low. | 1. | Add refrigerant. | |||
2. | Head pressure low. | 2. | Check refrigerant charge. | ||||
3. | Air ®lters dirty. | 3. | Clean or replace ®lters. | ||||
4. | Expansion valve power head defective. | 4. | Replace power head. | ||||
5. | Indoor coil partially iced. | 5. | Check | ||||
6. | Indoor air¯ow restricted. | 6. | Remove obstruction. | ||||
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| Suction Pressure High |
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1. | Unloaders not functioning. | 1. | Check unloader adjustments. Check unloader setting. | ||||
2. | Compressor valve defective. | 2. | See 06E compressor service literature. | ||||
3. | Heat load excessive. | 3. | Check for open doors or windows in vicinity of fan coil. | ||||
UNIT OPERATES TOO LONG OR CONTINUOUSLY |
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1. | Low refrigerant charge. | 1. | Add refrigerant. | ||||
2. | Control contacts fused. | 2. | Replace control. | ||||
3. | Air in system. | 3. | Purge and evacuate system. | ||||
4. | Partially plugged expansion valve or ®lter drier. | 4. | Clean or replace. | ||||
SYSTEM IS NOISY |
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1. | Piping vibration. | 1. | Support piping as required. | ||||
2. | Compressor noisy. | 2. | Check valve plates for valve noise. Replace compressor if bearings | ||||
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COMPRESSOR LOSES OIL |
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1. | Leak in system. | 1. | Repair leak. | ||||
2. | Crankcase heaters not energized during shutdown. | 2. | Check wiring and relays. Check heater and replace if | ||||
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FROSTED SUCTION LINE |
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| Expansion valve admitting excess refrigerant. | Adjust expansion valve. | ||||
HOT LIQUID LINE |
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1. | Shortage of refrigerant due to leak. | 1. | Repair leak and recharge. | ||||
| 2. | Expansion valve opens too wide. | 2. | Adjust expansion valve. | |||
FROSTED LIQUID LINE |
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| Restricted ®lter drier. | Remove restriction or replace. | ||||
COMPRESSOR WILL NOT UNLOAD |
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1. | Defective unloader. | 1. | Replace unloader. | ||||
2. | Defective capacity control solenoid valve. | 2. | Replace valve. | ||||
3. | Miswired capacity control liquid line solenoid. | 3. | Rewire correctly. | ||||
COMPRESSOR WILL NOT LOAD |
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1. | Miswired capacity control liquid line solenoid. | 1. | Rewire correctly. | ||||
2. | Defective capacity control solenoid valve. | 2. | Replace valve. | ||||
3. | Plugged strainer (high side). | 3. | Clean or replace strainer. | ||||
4. | Stuck or damaged unloader piston or piston ring(s). | 4. | Clean or replace the necessary parts. | ||||
CONTACTOR OPEN |
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1. | Power off. | 1. | Restore power. | ||||
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| 2. Fuses blown in ®eld power circuit. | 2. | After ®nding cause and correcting, replace with correct fuses. | |||
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| 3. No control power. | 3. | Check secondary fuses. Replace with correct type and size. Replace | |||
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| 4. No demand by unit control. |
| transformer if primary windings are receiving power. | |||
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| 4. | Check unit status at HSIO. Check alerts and alarms at HSIO. Cor- | ||||
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| 5. Fan status switch not closed. |
| rect as required and reset. | |||
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| 5. | Check continuity at fan status switch contacts. Check wiring from fan | ||||
6. | VFD overload function tripped. |
| status switch to PSIO no. 1, channel 12. | ||||
6. | Refer to separate VFD technical manual for troubleshooting instruc- | ||||||
7. | Motor leads loose. |
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7. | Check connections at motor lead junction box. | ||||||
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| 8. Motor windings open. | 8. | Check motor windings. | |||
9. | Single phasing. | 9. | Check for blown fuse. Check for loose connections at motor junction | ||||
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| 10. Belts broken or thrown. |
| box. | |||
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| 10. | Check belts. Replace as complete set if necessary. | ||||
11. | Fan status switch contacts defective. | 11. | Check for input signal at PSIO no. 1, channel 12. Replace switch if | ||||
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CONTACTOR CLOSED |
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1. | No output signal from control at PSIO no. 1, | 1. | Check alerts and alarms at HSIO. Check status at HSIO. | ||||
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| Replace PSIO no. 1. | ||
2. | Communication failure at VFD. | 2. | Check for input signal at VFD, terminals FI (+) and FC | ||||
3. | Fan status switch contacts defective. | 3. | Check switch continuity. Replace switch if defective. | ||||
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| LEGEND |
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HSIO Ð Human Sensory Input/Output Device |
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DSIO | Ð Processor Module |
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VFD | Ð Variable Frequency Drive |
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