Service Manual

SERVICE AND MAINTENANCE FAN COILS
496 08 8001 02 15
Specifications subject to change without notice.
Table 5 – FCM4 self−identifying resistor values
Heater Size
kW
Resistor Ohms
Nominal
No heater Open
9 11k
15 18k
20 24k
24 33k
30 39k
STATUS CODE 36, HEATER OUTPUT NOT SENSED WHEN
ENERGIZED:
Fan coil control is provided with circuitry to detect presence of
a 24−Vac signal on Electric Heater stage 1 and stage 2
outputs.
If fan coil control energizes either heater stage and does not
detect the 24−Vac signal on output, Status Code 36 will be
displayed on the STATUS LED Fan coil control will continue to
energize heater output(s) and adjust blower operation to a
safe airflow level for energized electric heat stage(s).
To find the fault, check for 24Vac on heater stage outputs. Fan
coil control or sensing circuit may be bad.
NOTE: It may be useful as an electric heater troubleshooting
procedure to disconnect the system communications to force
Status Code 16 enabling of emergency heat mode. It is difficult
to know which heater output is energized or not energized in
normal operation. When fan coil is operated in emergency
heat mode using electric heaters, both outputs are energized
and de−energized together. Terminal strip inputs to control can
then be connected R to W to turn on both electric heat
outputs. Heater output sensing circuits can then be checked to
resolve Status Code 36 or 37 problems.
STATUS CODE 41, BLOWER MOTOR FAULT:
If MOTOR LED is lit and flashing and motor does not run:
1. Check STATUS LED. If STATUS LED is indicating
Status Code 41, motor control has detected that the
motor will not come up to speed within 30 seconds of
being commanded to run or that the motor has been
slowed to below 250 rpm for more than 10 seconds
after coming up to speed. Motor wiring harness and fan
coil control are operating properly, do not replace.
2. Check to be sure that the blower wheel is not rubbing
the housing.
3. Check motor to be sure that the motor shaft is not
seized (motor control module must be removed and
electronics disconnected from windings to perform this
check properly).
4. Check motor windings section following instructions in
Section C. ECM Motor Troubleshooting.
If all these checks are normal, the motor control module may
need replacement.
STATUS CODE 16, SYSTEM COMMUNICATION FAULT:
If, at any time, system communications are not successful for
a period exceeding two minutes, the fan coil control will only
allow emergency heating or cooling operation using a
common thermostat, a non−communicating outdoor unit, and
the R, C, Y, O, W outdoor unit terminal strip connections and
will display Status Code 16 on the amber STATUS LED (see
section E, Emergency Heating and Cooling Modes). No further
fan coil troubleshooting information will be available at the
Observer wall control until communications are reestablished.
Check system wiring to be sure the Observer wall control is
powered and connections are made DX+ to DX+, DX− to DX−
etc. and wiring is not shorted. Mis−wiring or shorting of the
DX+, DX−, C, R communications wiring will not allow
successful communications. Correcting wiring faults will clear
the code and reestablish communications.
Shorting or mis−wiring the low voltage system wiring will not
cause damage to fan coil control or to Observer wall control
but may cause the low voltage fuse to open.
STATUS CODE 46, BROWNOUT CONDITION:
If the secondary voltage of the transformer falls below 15Vac
for a period exceeding four seconds, Status Code 46 will be
displayed on STATUS LED.
If system includes a non−communicating outdoor air
conditioner or heat pump, the Observer wall control will
command the fan coil to turn off Y output controlling
compressor.
When secondary voltage rises above 17Vac for more than four
seconds, the brownout condition is cleared and normal system
operation will resume subject to any minimum compressor off
delay function which may be in effect. Brownout does not
affect blower or electric heater operation.
STATUS CODE 53, OUTDOOR AIR TEMPERATURE
SENSOR FAULT:
If an OAT sensor is found at power−up, input is constantly
checked to be within a valid temperature range. If sensor is
found to be open or shorted at any time after initial validation,
Status Code 53 will be displayed at amber STATUS LED.
Check for faults in wiring connecting sensor to OAT terminals.
Using an Ohmmeter, check resistance of thermistor for a short
or open condition.
If thermistor is shorted or open, replace it to return the system
to normal operation. If fault is in the wiring connections,
correcting the fault will clear the code and return the system to
normal operation.
NOTE: If fault condition is an open thermistor or a wiring
problem that appears to be an open thermistor and the power
to the fan coil control is cycled off, the fault code will be
cleared on the next power−up but the fault will remain and
system operation will not be as expected. This is because on
power−up, the fan coil control cannot discern the difference
between an open sensor or if a sensor is not installed.
F. Emergency Heating and Cooling Modes
Fan coil control can provide emergency heating or cooling
using a common heat/cool thermostat in the event that there
are no system communications, fault is in Observer wall
control and no replacement is immediately available.
To activate these modes, the thermostat and outdoor unit must
be wired as a common heating/cooling system to fan coil
control RYWC terminals. Fan coil control must be powered
and displaying Status Code 16, System Communication Fault.
NOTE: These emergency modes do not provide the level of
comfort and efficiency expected by the consumer and should
only be activated when Observer wall control cannot be
replaced immediately.
SEQUENCE OF OPERATION
The FCM4 fan coil is designed for installation with Observer
communicating wall control. This fan coil will not respond to
commands provided by a common thermostat except under
certain emergency situations described in the Start Up and
Troubleshooting sub−section.
The Observer wall control uses temperature; humidity and
other data supplied from indoor and outdoor system