Fma4P, Fma4X, Wama Waxa - International comfort products FEM4 Service And Maintenance Instructions

SERVICE AND MAINTENANCE
FMA4P, WAMA, FMA4X, WAXA
WARNING
!
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal
injury or death.
Before installation or servicing system, always turn off
main power to system. There may be more than one
disconnect switch. Turn off accessory heater power if
applicable. Lock out and tag switch with a suitable
warning label.
FAN MOTOR
FMA4P, WAMA
The FMA4P and WAMA motor is three−speed ECM direct
drive. High−speed lead is black, medium−speed lead is red,
low−speed lead is blue, and common lead is purple. Be sure
proper blower speed has been selected.
The motor is turned on through two different routes. The first
occurs when thermostat calls for the fan in cooling, heat
pump, or fan−only mode. A 24−Vac signal is sent to relay,
causing relay to close its normally open contacts, turning fan
on.
The second occurs when there is a call for electric heat. A
24−Vac signal is sent to heater sequencer/relay, causing it to
close, directing 230V through the normally closed contact of
fan relay, turning fan on. The fan remains on until
sequencer/relay opens.
If motor does not run, test motor for an open winding or a
winding shorted to motor case. If either is present, replace
motor.
FMA4X, WAXA
The FMA4X and WAXA motor is five−speed direct drive. The
cooling speed tap is selected by connecting the green wire to
the desired motor tap number indicated on the motor plug.
For the electric heat fan speed selection connect the white
wire to the desired motor tap number indicated on the motor
plug.
The blower motor in this unit has blower−on and blower−off
delays. The blower−on delay is 0−30 seconds and will keep
the motor running after a heating or cooling call ends.
If motor does not run, test motor for an open winding or a
winding shorted to motor case. If either is present, replace
motor.
ELECTRIC HEATER SERVICE
Service can be completed with heater in place. Shut off
power before servicing.
A. Limit Switch
Refer to Electric Heater Kit Function and Troubleshooting
section of this manual.
B. Sequencer
Refer to Electric Heater Kit Function and Troubleshooting
section of this manual.
C. Transformer
A 40−VA transformer supplies 24−V power for control circuit.
Check for 208/230V on primary side of transformer. If present,
check for 24V on secondary side.
NOTE: Transformer is fused. Do not short circuit.
496 08 8001 00
D. Fan Relay
Relay coil is 24−V. Check for proper control voltage. Replace
relay if faulty.
CLEANING OR REPLACING REFRIGERANT
FLOW−CONTROL DEVICE
The FMA4P and WAMA piston can be removed and cleaned
if believed to be plugged. This unit's piston is unique and
replacements are available from FAST.
The filter drier should be located on the liquid line at the
indoor unit to prevent particulate from plugging the piston.
The FMA4X and WAXA fan coils use an R−410A TXV. The
TXV's are preset at the factory and do not need adjustment
for reliable operation. Reference the outdoor unit instructions
to properly charge the unit to the correct subcooling. For
optimal performance, adjust the TXV so that 6º F of
superheat is measured at the outdoor unit's vapor service
valve when the indoor return air is 80º F DB/67º F WB and
outdoor ambient is 82º F DB. To increase superheat turn the
TXV adjustment stem clockwise no more than one rotation at
a time. After an adjustment is made, wait until the superheat
temperature has been stable for 15 minutes before making
further adjustments.
SEQUENCE OF OPERATION
A. Condensing Unit
COOLING
When thermostat calls for cooling, the circuit between R and
G is complete and single−pole single−throw relay FR is
energized. The normally open contacts close causing blower
to operate.
The circuit between R and Y is also complete. This
completed circuit causes contactor in outdoor unit to close
which starts compressor and outdoor fan.
HEATING
When thermostat calls for heating and FAN switch is set on
AUTO, the circuit between R and W is complete. The heater
sequence SEQ is energized which closes contacts of relay.
There will be a time delay. This completed circuit energizes all
heating elements HTR and blower motor.
B. Heat Pump
COOLING
On a call for cooling, the thermostat makes circuits R−O, R−Y,
and R−G. Circuit R−O energizes reversing valve, switching it
to cooling position. Circuit R−Y energizes contactor starting
outdoor fan motor and compressor. Circuit R−G energizes
indoor unit blower relay starting indoor blower motor.
When thermostat is satisfied, its contacts open de−energizing
contactor reversing valve and blower relay. This stops
compressor and fan motors.
HEATING
On a call for heating, the thermostat makes circuits R−Y and
R−G. Circuit R−Y energizes contactor starting outdoor fan
motor and compressor. Circuit R−G energizes indoor blower
relay starting blower motor.
Should temperature continue to fall, R−W circuit is made
through second−stage room thermostat bulb. Circuit R−W
energizes a sequencer bringing on supplemental electric
heat.
When thermostat is satisfied, its contacts open de−energizing
contactor and sequencer. All heaters and motors should stop.
Specifications subject to change without notice.
FAN COILS
FMA4P, WAMA
FMA4X, WAXA
17