KRUEGER A Series User Manual

38
KHF - SERIES A FAN COIL UNITS
INSTALLATION, OPERATION, AND MAINTENANCE MANUAL
EC MOTOR
PROBLEM POSSIBLE CAUSE CORRECTIVE ACTION
NO AIRFLOW
[EC MOTOR]
No demand Verify thermostat or control is calling for heating or cooling.
Fan speed is not commanded Verify fan run command is present at Fan Relay Board.
No power to motor. Possible blown fuse or open circuit
breaker
Verify line voltage at motor terminals. Replace fuse or reset circuit breaker as needed.
Incorrect voltage applied Verify proper voltage to unit per unit label.
Improper wiring connections
Verify wiring. If Fan Coil Relay board present, verify all jumpers and harnesses installed on Fan Relay Board.
Refer to Fan Coil Relay Board Troubleshooting Guide.
Three speed switch in OFF position Verify three speed switch, if present, is set to desired speed.
Loss of 24V power Refer to Fan Relay Board Troubleshooting Guide.
Drain pan oat switch tripped
If drain pan oat switch is present, verify drain pan is not full. Verify operation of oat switch.
Adjust switch position if needed.
Drain pan oat switch fault
Verify operation of drain pan oat switch, if present. Disconnect switch and use volt-ohm meter to verify
continuity of switch and of wiring. Replace switch if faulty.
Low temperature cutout has tripped
If low temperature cutout is present. Examine coil for signs of freezing. Verify adjustment of freeze stat.
Disconnect switch and use volt-ohm meter to verify continuity. Replace switch if faulty.
Blower jammed
Remove power from unit. Clear blockage.
Verify blower is not damaged and rotates freely while motor is not energized.
Motor seized
Remove power from unit. Verify motor rotates freely by hand with blower disconnected. If not, replace motor.
Note: EC motors may not rotate freely as the rotor aligns with the stator magnets."
Motor overloaded
Verify motor is not overheated. Remove power from unit. Check to ensure blower rotates freely with motor
disconnected. Verify proper duct static. Wait for motor to cool down and verify motor start. If motor overheats
again, replace motor.
PWM board faulted
Refer to PWM board status LEDs. Verify voltage input, wiring and connections. Refer to PWM board IOM.
Replace PWM board if fault returns.
NO AIR FLOW
[EC MOTOR]
No control signal
EC motors may run at idle speed if they lose PWM signal while enabled. Verify PWM signal at motor connector.
Refer to PWM board IOM.
Wiring harness improperly seated Unplug harness and re-install, making sure plugs are fully seated.
Wiring harness(es) open or intermittent Replace harness(es). Refer to PWM board IOM.
Damaged motor harness Replace motor harness.
FAN MOTOR SURGES
[EC MOTOR]
Loose motor wiring Reseat motor connector. Tighten all motor connections.
Loose control wiring Verify and/or tighten all control connections.
Intermittent control device
Verify operation of any control device such as drain pan oat switch, freeze stat, thermostat, etc.
When in doubt, jumper out and verify fan operation.
[EC motor] Fan speed adjustment outside operating range
Refer to Fan Calibration curve on unit. Adjust speed on PWM Controller to value that will allow motor to start.
See instructions for Adjusting EC Motor Speed.
[EC motor] Faulty PWM signal Verify PWM signal at motor connector. Refer to PWM board IOM.
Blower Set Screw loose Tighten Screw onto motor shaft.
Improper duct connections
Verify proper ductwork to unit. Verify ductwork is installed per SMACNA and ASHRAE guidelines.
Incorrectly sized ducts can cause motor surging.
ESP (external static pressure) too high
Verify dampers, if present, are not closed. Verify there are no obstructions in the discharge ductwork and/or at
the plenum opening. Verify lter is not dirty and does not obstruct airow.
TROUBLESHOOTING (CONTINUED)

KRUEGER A Series Specifications

General

Brand	KRUEGER
Model	A Series
Category	Fan
Language	English