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SAFETY CONSIDERATIONS
Improper installation, adjustment, alteration, service, maintenance,
or use can cause explosion, fire, electrical shock, or other
conditions which may cause personal injury or property damage.
Consult a qualified installer, service agency, or your distributor or
branch for information or assistance. The qualified installer or
agency must use factory-authorized kits or accessories when
modifying this product. Refer to the individual installation instruc-
tions packaged with the kits or accessories for detailed informa-
tion.
Follow all safety codes. Wear safety glasses and work gloves. Use
quenching cloth for brazing operations. Have fire extinguisher
available. Read these instructions thoroughly and follow all
warnings or cautions attached to the unit. Consult local building
codes and National Electrical Code (NEC) for special installation
requirements.
It is important to recognize safety information. This is the
safety-alert symbol
. When you see this symbol on the unit or in
instructions and manuals, be alert to the potential for personal
injury.
Understand the signal words DANGER, WARNING, and CAU-
TION. These words are used with the safety-alert symbol. DAN-
GER identifies the most serious hazards which will result in severe
personal injury or death. WARNING signifies hazards which
could result in personal injury or death. CAUTION is used to
identify unsafe practices which would result in minor personal
injury or product and property damage.
CAUTION: Puron (R-410A) systems operate at higher
pressures than R-22 systems. Do not use R-22 service
equipment or components on R-410A equipment. Ensure
service equipment is rated for R-410A.
INTRODUCTION
The "F" series fan coil units are designed for flexibility in a variety
of applications, meeting upflow, horizontal, or downflow require-
ments. Units are available in 1-1/2 through 5 ton nominal cooling
capacities. Factory-authorized, field-installed electric heater pack-
ages are available in 3 through 30 kilowatts.
WARNING: Before installing or servicing fan coil,
always turn off all power to unit. There may be more than
1 disconnect switch. Turn off accessory heater power if
applicable. Electrical shock can cause personal injury or
death.
UNIT IDENTIFICATION
The 16 position numbering chart allows identification of all
available fan coil units. (See Fig. 2.)
FA4A, FB4A, FC4B, FF1D, FH4A, AND FX4A
CIRCUIT BOARD
FUNCTION AND TROUBLESHOOTING
CES0130003-00 and -01 PCB
This section of the service manual describes the CESO130003-00
and -01 PCB by examining the functional operation of the PCB
components.
I. PRINTED CIRCUIT BOARD (PCB) COMPONENT
LAYOUT AND DESCRIPTION
Layout of the actual PCB is depicted in Fig. 3A.
1. The low-voltage stripped leads are used to connect the 24-v
side of transformer to indoor thermostat and outdoor
section.
2. A 5-amp fuse is used to protect the low-voltage transformer
secondary.
3. The fan relay is controlled by thermostat and turns fan on
and off.
4. A plug is used as the connection for PCB power and electric
heaters. Note the pin numbers on plug.
5. A time-delay relay circuit keeps fan motor running for
approximately 90 sec after G is de-energized. The time-
delay can be defeated by cutting jumper JW1.
II. UNIT FUNCTIONS
A. Transformer
1. Proper Wiring of Transformer Primary or High Side
Yellow wire from Molex plug is wired to C terminal on
transformer and black wire from PCB relay (normally-
open) terminal is wired to 208v or 230v terminal on
transformer. Units are factory wired at 230v terminal.
2. Proper Wiring of Transformer Secondary or 24-v Side
Red wire of transformer is wired to T terminal on PCB and
brown wire of transformer is wired to C terminal on PCB.
NOTE: T terminal on PCB is used to protect transformer. T
terminal is connected through the fuse to R terminal on PCB.
B. Indoor Fan
1. Wiring (See Fig. 3B for FF1D typical wiring diagram.)
Indoor fan motor yellow lead is wired to C terminal on
transformer. The red, blue, or black speed lead is wired to
SPT terminal on fan relay part of PCB. Units are factory
wired on medium speed (blue lead connected).
NOTE: Unused fan speed leads must be capped or taped off to
prevent direct short to cabinet surface.
2. Functional Control
a. Thermostat and Relay Control
When thermostat calls for the fan in cooling, heat pump,
heating, or fan-only mode, a 24-vac signal is sent to
relay. This causes the relay to close its normally-open
contacts, turning on fan. When thermostat no longer calls
for the fan, the signal sent to relay is turned off and relay
opens causing fan to turn off after a 90-sec fan-off delay.
b. Sequencer/Electric Heat Relay Interlock
The fan will also operate whenever there is a call for
electric heat, even if fan relay is not energized. This
happens because fan is interlocked with first stage of
electric heat through the normally-closed contact of fan
relay.
NOTE: The fan interlock is only connected to first stage electric
heat W2. W3 and E do not contain an interlock with fan. See
outdoor thermostat Installation Instructions when electric heat
staging is desired.
C. Electric Heat
NOTE: Models FF1A/FF1B/FF1C use sequencers for electric
heat. Model FF1D uses DC rectified relays for electric heat.
(See Fig. 3C.)
When thermostat calls for electric heat, a 24-vac signal is sent to
sequencer/heat relay through W2, causing first stage to turn on.
W3 and E also receive signal if wired in with W2. The signal sent
to W2 causes first stage to turn on. If W3 and E are not wired to
W2, the sequencers/heat relays can be controlled individually to
stage additional electric heat. The sequence control is described in
the following section:
—2—
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Troubleshooting
