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Appendix I
Trouble Shooting
Problem Cause Solution
Unit will not turn on. External wiring not connected. Check external wiring.
Internal wiring not making contact. Check the wiring in the control box.
Occ./Unocc. control circuit is open. Close circuit.
Unit will not turn off. External terminal strip wiring. Check if high or low speed control contacts are
closed on the terminal strip.
Air from supply Imbalance of supply and exhaust air. Check filters and enthalpy wheel for
diffusers too cold. blockage. Check balance of airflow. Install
post heat module.
Unit makes an Blower wheel out of alignment. Remove the motor/blower assembly.
annoying noise. Adjust blower wheel.
Enthalpy wheel brush seal not Check for proper seal operation.
functioning properly.
Enthalpy wheel not Electrical supply interrupted. Check unit circuit breaker. Check two wire
running. service connector on motor.
Drive motor capacitor. Check capacitor connections. Check motor
operation with a new capacitor.
Drive motor failure. Check the drive motor.
Drive motor relay in control box. Check relay wiring. Check relay operation.
Drive belt. Check for drive belt derailment off of drive
pulley or failure.
Drive pulley. Check for securely fastened pulley on
motor shaft.
Free cooling contact closed. Open contact on external terminal block of unit.
Motor and blower Electrical supply interrupted. Check unit circuit breaker. Check three wire
not functioning. service connector on each motor.
Fan motor capacitor. Check capacitor connections. Check motor
operation with a new capacitor.
Fan motor failure. Check fan motor.
Fan motor relay in control box. Check relay wiring. Check relay operation.
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