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RPB-IOM (06-22) 131782-B
TROUBLESHOOTING—CONTINUED
Table 19. General Troubleshooting
Symptom Probable Cause Remedy
D. Insufficient
heat with
heater
operating
1. Dirty filters in blower system Clean or replace filters
2. Incorrect manifold pressure Check manifold pressure (refer to Measure and Adjust Manifold (Outlet)
Gas Pressure section)
3. Limit control cycling on Check air throughput
4. Improper thermostat location or adjustment Refer to thermostat manufacturer’s instructions
5. Belt slipping on blower Adjust belt tension (refer to Checking and Adjusting Belt Tension section)
6. Fan control improperly wired Ensure that wiring connections are in accordance with wiring diagram
7. Defective fan control Replace fan control
8. Blower set for too low temperature rise Decrease blower speed (refer to Adjusting Blower Speed section) or
increase static pressure
E. Motor will
not run
1. Circuit open Check wiring and connections
2. Inoperative fan control Replace fan control
3. Fan control improperly wired Ensure that wiring connections are in accordance with wiring diagram
4. Inoperative contactor Replace contactor
5. Defective motor Replace motor
F. Motor
turns ON and
OFF while
operating
1. Motor overload device cycling Verify motor load against motor rating plate
Replace motor or overload device
2. Three-phase motor rotating in opposite
direction
Interchange two legs of supply connections
G. Motor
cuts out on
overload
1. Improper motor pulley adjustment Ensure that motor pulley is properly-adjusted (refer to Adjusting Blower
Speed section)
2. Improper static pressure on duct system Adjust dampers in duct system
3. Low voltage Check power supply
—Continued
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