KRUEGER A Series User Manual

41
KHF - SERIES A FAN COIL UNITS
INSTALLATION, OPERATION, AND MAINTENANCE MANUAL
ELECTRIC HEATER
PROBLEM POSSIBLE CAUSE CORRECTIVE ACTION
ELECTRIC HEAT
WILL NOT OPERATE
CAUTION: UNIT MAY BE
EXTREMELY HOT. TAKE
GREAT CARE WHEN
TROUBLESHOOTING.
Insucient airow Verify proper airow.
Loss of demand Verify thermostat or control is calling for heating. Verify demand voltage is present at unit.
[24V units] Loss of demand Verify 24V control signal at ‘W’ terminal during demand.
[24V units] Loss of 24V Verify integrity of fuse on Fan Relay Board and replace if needed. Refer to Fan Relay Board Troubleshooting Guide.
No airow. Electric heat will not operate unless fan motor is enabled. Verify fan speed is commanded.
Damaged primary limit wire harness
Disconnect primary limit wire harness (the purple wire harness coming out of the heater section.) Verify
continuity across wire harness. If no continuity, check if primary limit is tripped. If primary limit is veried
good, remove power from unit, disconnect primary limit wire harness, and measure continuity of wire harness.
Replace if bad.
Primary limit switch tripped.
Verify no loss of demand to unit. Verify that voltage exists on magnetic heater contactor during demand for
heat. If demand reaches unit but not contactor, primary limit is tripped. The primary limit switch(es) will auto-
reset once the unit cools down. If unit is hot, wait for heater to cool down. This may take up to an hour.
Secondary limit switch tripped
The secondary limit may be manually reset. If unit is hot, wait for the heater to cool down.
This may take up to an hour. Reset switch(es). Verify if heater will start.
Improper wiring connections Verify wiring to schematic.
Open or damaged heater elements
With power removed, disconnect heater wire harnesses. (These are the harnesses with the black plugs.) Use a
volt-ohm meter to measure resistance across the electric heat power harness coming out of the heater section.
If the meter measures an open or shorted circuit, inspect the heating elements.
Damaged electric heat wire harness
With power removed, disconnect heater wire harnesses.
Use a volt-ohm meter to verify continuity of electric heat power harness wires in the control enclosure section.
Primary Limit switch fault
With power removed and heater cool, remove primary limit switch.
Verify continuity across switch. Replace switch if open.
Secondary Limit switch fault
With power removed and heater cool, remove secondary limit switch.
Verify switch is reset. Verify continuity across switch. Replace switch if open.
ELECTRIC HEAT
WILL NOT OPERATE
CAUTION: UNIT MAY BE
EXTREMELY HOT. TAKE
GREAT CARE WHEN
TROUBLESHOOTING.
[Magnetic contactor] Electric heat contactor fault
Verify heating demand voltage is at magnetic electric heat contactor control coil terminals. If power is present
but contactor is not actuated, replace contactor. To verify contactor: with power removed, unwire contactor and
verify continuity across contacts when manually operated. Cover of contactor will need to be removed to access
manual operator. Replace contactor if faulty.
[Solid state relay] electric heat safety contactor fault
Verify control voltage is at magnetic electric heat contactor control coil terminals.
If power is present at coil but contactor is not actuated, replace contactor.
[Solid state relay] Solid State Relay fault
Verify heating demand (control voltage) is at solid state relay control terminals.
If power is present but relay is not actuated, replace relay.
[Solid state relay proportional control] Heat controller fault
Verify DC control signal is present at controller input terminals.
Verify that output control voltage to solid state relay varies with variation in input. Replace controller if not.
ELECTRIC HEAT SHUTS
DOWN UNEXPECTEDLY
CAUTION: UNIT MAY BE
EXTREMELY HOT. TAKE
GREAT CARE WHEN
TROUBLE- SHOOTING.
Loss of demand
Verify that thermostat or control command signal is not dropping out.
Verify voltage is present at unit during demand for heat.
[24V units] Loss of demand
Verify that signal from thermostat or control is not dropping out.
During demand, there needs to be 24V on 'W1' terminal of Fan Relay board.
Primary limit switch tripped
Verify no loss of demand to unit. Verify that voltage exists on heater contactor during demand for heat. If
demand reaches unit but not contactor, primary limit is tripped. The primary limit switch(es) will auto-reset
once the unit cools down. If unit is hot, wait for heater to cool down. This may take up to an hour. If limit trips
again, verify heater is not overheating.
Secondary limit switch tripped
The secondary limit may be manually reset. If unit is hot, wait for the heater to cool down.
This may take up to an hour. Reset switch(es). If limits trip again, verify heater is not overheating.
Loss of fan speed command Heater will not operate if fan is not enabled.
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.
Loose wiring Verify and/or tighten all wiring connections.
TROUBLESHOOTING (CONTINUED)

KRUEGER A Series Specifications

General

Brand	KRUEGER
Model	A Series
Category	Fan
Language	English