Service Manual

SERVICE AND MAINTENANCE FAN COILS
10 496 08 8001 02
Specifications subject to change without notice.
which initiates Superdehumidification and reduces the airflow
to 50 percent of cooling.
HEATING
The base heat pump only heating airflow is determined by the
SYSTEM TYPE selection on the Easy Select Board. If
HP−EFFICIENCY is selected, the airflow is the same as
Cooling. IF HP−COMFORT is selected, the airflow is 315 CFM
per ton. The airflow will adjust up if necessary when auxiliary
heating is required. When both the Y/Y2 and W1 or W2
terminals are energized, the motor will run the higher of the
heat pump or electric heat airflows. Super Comfort Heat mode
is initiated when the indoor control removes the G signal from
the board. This slows the motor to 75 percent of heat pump
airflow. If the CFM adjust is set to LO, it will deliver 67.5
percent of heat pump airflow during Super Comfort Heat
mode.
TROUBLESHOOTING
A. Troubleshooting Easy Select Board (FVM4)
If Traces Are Overheated on Back of PCB:
Usually whenever there is a trace broken on PCB, it means
either there has been a high−voltage short or high voltage has
been applied to low−voltage circuit. This can be prevented by
making sure PCB is wired correctly before fan coil has power
applied to it.
If PCB Fuse Keeps Blowing:
When low−voltage fuse blows, it means transformer would
have blown if fuse had not been in circuit to protect it. The fuse
usually blows when there is a high current drawn on
transformer, high voltage applied to low−voltage circuit, or a
direct secondary short. When there is a high current drawn on
transformer, it is most likely because transformer has been
shorted or system is trying to draw more Vac than transformer
rating allows. When fuse blows because of high voltage, the
system has mixed high and low−voltage signals.
1. Check transformer and thermostat wiring. (See
Figure 5.) Be sure transformer is not shorting out
because thermostat wires are miswired.
2. Check wiring of relays. (See Figure 5.) Be sure
low−voltage and high−voltage wiring are connected to
proper sequencers.
3. Check VA draw on transformer. If VA draw is more than
VA rating of transformer, fuse will blow. If this is the
case, replace transformer with one that has a higher VA
rating.
B. Troubleshooting Common Problems
Airflow Too Low:
Y1 instead of Y/Y2 on single−speed air conditioner or heat
pump application. Y1 input is only for two−speed applications.
Using this terminal will deliver about 60 percent of full cooling
airflow.
Wrong Easy Select Board selection. Selecting an outdoor unit
or electric heater smaller than actually installed will result in
low airflow for the application.
G not energized with call for cooling or heating. This triggers
Super Comfort Heat or SuperDehumidify mode which delivers
50 percent of cooling airflow.
J1 jumper pulled with no dehumidistat installed. The J1 jumper
ties the DH terminal to R and is installed at the factory. When
pulled, a dehumidistat supplies a 24−V signal to DH when
there is no call for dehumidification (reverse logic). When there
is no signal on DH, the motor reduces airflow to 80 percent for
better dehumidification.
Airflow Too High:
Wrong Easy Select Board selection. Fan coil is factory set for
the largest outdoor unit and largest electric heater. Select
sizes that are actually installed.
Continuous fan set too high for two−speed applications. Set to
MED or LO.
Motor Will Not Stop:
The off delay on any W call is one minute and cannot be
overridden.
Some power−stealing thermostats could bleed enough voltage
to cause motor to run slowly when there is no heating or
cooling call. Disconnect thermostat wires and wait two minutes
to see if motor stops. If it stops, replace thermostat, or install
resistor per thermostat installation instructions.
Motor Will Not Start:
See following section, “Troubleshooting ECM 5.0 Motor and
Controls
C. Troubleshooting ECM 5.0 Motor and Controls
ELECTRICAL OPERATIONS HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
High voltage is always present at motor. Disconnect
power to unit before removing or replacing connectors
or servicing motor. Wait at least five minutes after
disconnecting power before opening motor.
CAUTION
!
The ECM/ICM motor used with this product contains two parts:
the control module and the motor winding section. Do not
assume the motor or module is defective if it will not start. Go
through the steps described below before replacing control
module, Easy Select Board or entire motor. The control
module is available as a replacement part.
D. If Motor Turns Slowly:
1. It is normal operation to run noticeably slower if G
terminal is not energized in cooling or heat pump
heating modes.
2. Attach blower access panel. Motor may appear to run
slowly if access panel is removed.
E. If Motor Does Not Run:
Turn power off, wait five minutes and check the following:
1. With power turned off, check 5−amp fuse on Easy
Select Board.
2. Check all plugs and receptacles for any deformation or
corrosion that could cause bad connections. Be sure
plugs are fully seated.
ELECTRICAL OPERATION HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
DO NOT remove or apply 5−pin plug on motor with
power on. Arcing could occur, which can damage
control module
CAUTION
!
Turn power back on and check the following:
3. Check for 24Vac on SEC1 and SEC2. If no voltage is
present, check transformer.
4. Verify that approximately 230Vac is present at motor.
5. Verify low voltage control signals to motor according to
procedure below.