Troubleshooting
Symptom | Possible Cause | Corrective Action | |
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| Blown fuse or open circuit | Replace fuse or reset circuit breaker and check amps.. | |
| breaker.. |
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Blower Fails to | Defective motor or capacitor.. | Replace.. | |
Motor starter overloaded.. |
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Operate | Reset starter and check amps.. | ||
| Electrical.. | Check for On/Off switches.. Check for correct supply voltage.. | |
| Drive.. | Check for broken or loose belts.. Tighten loose pulleys.. | |
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| Control power (24 Vac) wiring | Shorten wiring run to mechanical room or install a relay | |
| run is too long (resistance | which will turn unit on/off (C/F for relay information).. | |
| should not exceed 0..75 ohms).. |
| |
Motor Starters | Incoming supply power is | Need to increase supply power or use a special control | |
‘Chatter’ | |||
less than anticipated.. Voltage | transformer which is sized for the actual supply power.. | ||
or | |||
supplied to starter coil must |
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Do Not Pull In |
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be within +10% / |
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| nominal voltage stated on |
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| the coil.. |
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| Cfm too high.. | Check cfm and adjust drives if needed.. | |
| Static pressures are higher or | If higher, ductwork should be improved.. | |
| lower than design.. | If lower, fan rpm should be lower.. | |
Motor Over Amps | Blower rotation is incorrect.. | Check rotation and reverse if necessary.. | |
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| Motor voltage incorrect.. | Check motor nameplate versus supplied voltage.. | |
| Motor horsepower too low.. | See specifications and catalog for fan curves to determine if | |
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| horsepower is sufficient.. | |
| Shorted windings in motor.. | Replace motor.. | |
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| Unit damper not fully open.. | Adjust damper linkage or replace damper motor.. | |
| System static pressure too high | Improve ductwork to eliminate losses using good duct | |
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| practices.. | |
| Blower speed too low.. | Check for correct drives and rpm with catalog data.. | |
| Fan wheels are operating | For | |
Low Airflow (cfm) | backwards.. | ||
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| Dirty filter or energy wheel.. | Follow cleaning procedures in Routine Maintenance section.. | |
| Leaks in ductwork.. | Repair.. | |
| Elbows or other obstructions | Correct or improve ductwork.. | |
| may be obstructing fan outlet.. |
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| Belt slippage.. | Adjust belt tension.. | |
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| Blower fan speed too high.. | Check for correct fan rpm.. Decrease fan speed if necessary.. | |
High Airflow (cfm) | Filter(s) not in place.. | Install filters.. | |
Insufficient static pressure (Ps) | Induce Ps into system ductwork.. Make sure grilles and | ||
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| (airflow resistance).. | access doors are installed.. Decrease fan speed if necessary.. |
* Always provide the unit model and serial number when requesting parts or service information. * Always check motor amps and compare to nameplate rating.
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