Service Manual

16
3. If unit still will not run defrost, remove thermostat
pigtail harness from board and perform checks
directly on input pins with jumper wires. The pigtail
may have a bad connection or be mis- wired.
FAST# 1185790 DEFROST CONTROL
This defrost control is used in most non- communicating
Performance Series heat pumps with R- 410A refrigerant
and has all the same functionality, speedups,
troubleshooting as the FAST# 1174185 except for the forced
defrost timing when Quiet Shift- 2 is enabled.
Quiet Shift- 2 (non- communicating)
Quiet shift- 2 is a field selectable defrost mode (factory set to
OFF), which will reduce the occasional noise that could be
heard at the start of defrost cycle and restarting of heating
cycle. It is selected by placing DIP switch 3 on defrost board
in the ON position.
When Quiet Shift- 2 switch is placed in ON position, and
defrost is initiated, the following sequence of operation will
occur: The compressor will be de- energized for
approximately 1 minute, then the reversing valve will be
energized. A few seconds later, the compressor will be
re- energized and the normal defrost cycle starts. Once
defrost termination conditions have been met, the following
sequence will occur: The compressor will be de- energized
for approximately 1 minute, then the reversing valve will be
de- energized. A few seconds later, the compressor will be
re- energized and the normal heating cycle starts.
OF2
O
F1
ON
QUIET
SHIFT
120
30
60
60
30
90
INTERVAL TIMER
OFF
P3
DFT
O R W
2
Y C
T2 C C O
DFT
T1 Y
P1
J1
SPEEDUP
A05378
Fig. 10 – FAST# 1185790 Defrost Control
ECM Fan Motor (single stage equipment)
Some single stage outdoor units will be equipped with ECM
fan motors. For suspected ECM motor electrical failures,
first check for loose or faulty electrical connections. ECM
motors are not wired to the capacitor. A reference for the
wires is listed in the table below:
Table 3—ECM Fan Motor Wires
TERMINAL DESCRIPTION COLOR
1/4” Non insul a ted Q.C . Speed, Common (low Voltage) BRN/YEL
1/4” Insulated Q.C. AC line (high voltage) YEL
1/4” Non insul a ted Q.C . Speed (low voltage) BLU/YEL
#8 Non insulated ring Ground GRN/YEL
1/4” Insulated Q.C. AC line (high voltage) BLK
The low voltage wires should see 24VAC when the
contactor is engaged. The high voltage wires should see
230VAC as long as 230VAC is being supplied to the field
side of the contactor. The ECM motor will not operate
unless both 24VAC and 230VAC are being supplied. Refer
to the wiring diagram to determine where each wire should
be connected to the contactor. If connections are secure,
the motor is wired properly, proper voltages are present, and
the ECM motor is still not operational, replace the ECM
motor.
If utilizing a low ambient cooling kit, the ECM motor will not
function properly. The ECM motor will need to be replaced
with a PSC fan motor and fan blade specified in the
accessory lists for the unit and wired per the wiring diagram.
If the outdoor ECM fan motor fails to start and run:
S Check the high- voltage supply. The unit need not
be running to check high voltage, but the power
must be on.
S If the 230vac is present, disconnect the blu/yel wire
from ODF on the control board, and the brn/yel
wire from the contactor coil. Set a voltmeter on an
AC voltage scale and check across the ODF
terminal on the control board and the coil terminal
on the contactor. There should be a control signal
reading of 24vac.
S First check voltage with the motor disconnected. If
no control voltage is present, check control- board
connections. If connections are good, replace the
control board.
S If voltage is present, reconnect the motor and
check again. Shut down the unit to reconnect the
motor and restart the unit to complete this
troubleshooting procedure. If control voltage is no
longer present or motor fails to respond, check
motor connections.
S If connections are good, replace the motor.
PSC Fan Motor
The fan motor rotates the fan blade that draws air through
the outdoor coil to exchange heat between the refrigerant
and the air. Motors are totally enclosed to increase reliability.
This eliminates the need for a rain shield. For the correct
position of fan blade assembly, the fan hub should be flush
with the motor shaft. Replacement motors and blades may
vary slightly.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Turn off all power before servicing or replacing fan motor. Be
sure unit main power switch is turned off.
!
WARNING