COMPRESSOR FAILURE
If the System is in Cooling or Dehumidification Mode —
After 5 minutes of operation, if the temperature of the in-
door coil is not 4° F less than at the time the call for cooling
started, then a compressor failure is indicated on the remote
controller LCD display.
If the System is in Heat Pump Heating Mode (38BK only)
—After5minutesofoperation,ifthetemperatureindi-
cated by the outdoor coil thermistor is not 4° F less than at
the time the call for heating started, then a compressor fail-
ure is indicated.
REVERSING VALVE FAILURE (38BK Only)
If the System is in Cooling or Dehumidification Mode — After
5 minutes of operation, if the temperature at the indoor coil
is 4° F more than at the time the call for cooling started, then
a reversing valve failure is indicated.
If the System is in Heat Pump Heating Mode — After 5 min-
utes of operation, if the temperature indicated by the out-
door coil is 4° F more than at the time the call for heating
started, then a reversing valve failure is indicated.
System Safeties and Interlocks
INDOOR FAN FAILURE — If the indoor fan rpm shows
greater than 800 rpm for 30 seconds with the fan in the off
mode, then this test indicates an indoor fan failure. Also, if
the indoor fan rpm is greater than 1700 rpm for 30 seconds,
then this test indicates an indoor fan failure.
COMPRESSOR SHOR T-CYCLING PROTECTION — There
is a time delay of 3 minutes between compressor turning off
and turning back on.
INDOOR COIL FREEZE PROTECTION (Cooling or De-
humidification Mode Only) — If the indoor coil tempera-
ture is less than or equal to 32 F for 10 minutes after the
compressor has started, then the compressor and outdoor fan
are turned off. The indoor fan continues to run at the user-
selected speed until the indoor coil reaches 44 F. At that time,
the compressor and outdoor fan will restart.
INDOOR COIL HIGH-TEMPERATURE PROTECTION
(Heat Pump Systems Only) — If indoor coil temperature is
greater than or equal to 135 F, the outdoor fan shuts down.
The outdoor fan will restart automatically when the indoor
coil temperature drops to 120 F.
TROUBLESHOOTING
See Table 8 and Fig. 24 and 25 to assist in troubleshooting
the 40QN fan coil units.
Table 8 — Troubleshooting
PROBLEM POTENTIAL SOURCE ACTION
Unit does not operate
Circuit breaker has tripped or fuse is blown Reset the circuit breaker or replace the fuse.
Power failure
Restart fan coil unit operation when power is
restored.
Voltage is too low Confirm the available voltage.
Insufficient Cooling
Air filter is blocked with dust Clean the air filter.
Temperature is not set properly Check and reset if necessary.
Window(s) and/or door(s) are open Close window(s) and door(s).
Outdoor unit is obstructed Remove the obstruction.
Fan speed is too low Change the fan speed
Operation mode is set to fan or auto. mode
Change to cooling operation or reset temperature
(using remote controller).
Insufficient Heating*
Air filter is blocked with dust Clean the air filter.
Temperature is not set properly Check and reset if necessary.
Window(s) and/or door(s) are open Close window(s) and door(s).
Outdoor unit is obstructed Remove the obstruction.
Unit stops during operation
Off timer is operating Turn off the off timer function.
Room temperature has reached the programmed
set point
Normal unit operation.
*Heat pump systems only.
15
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