Trane 4TWL6036A1000A Service Facts page 12

D D e e f f r r o o s s t t C C o o n n t t r r o o l l
Table 3. LED FAULT CODES (continued)
LED
FAULT FAULT DESCRIPTION
CODES
5 FLASH Soft Lock Out
Defrost cycles too close
6 FLASH
together
Low Ambient Soft Lockout.
Outdoor temperature
9 FLASH
dropped below 3°F. (OFF at
-12°F/ON at 3°F)
1. Initiate Adaptive/Timed Limp Mode so long as Coil
Temp Sensor is functional. Monitor actual time in
defrost and add or reduce run time until next forced
defrost based on achieving a 4 minute (+/-1) defrost
period.
2. This defrost control utilizes a safety strategy called
"Adaptive Limp Mode". Adaptive limp mode is
defined as a timed heating mode following rapid
defrosts (accumulated heating times between
defrost totaling less than 15 minutes). Once invoked
the DFC will limit defrost periods and maximize
heating capacity. While in adaptive limp mode the
DFC will monitor heating and defrost periods for no
longer than 10 cycles. The DFC will then release the
board to demand defrost; however, if the LPCO
trips while in limp mode the system will initiate a
soft lockout and exit limp mode.
If both Coil Temp Sensor and Ambient Temp
Sensor have failed, initiate a 5 minute forced
defrost every 60 minutes of run time. This in
conjunction with the normal low pressure trip, will
initiate a soft lockout.
a. A short heating cycle that enters defrost in 15
minutes or less and/or enters two more defrosts
with less than 15 minutes of accumulative run
time each will enter an Adaptive Limp Mode (6
Flash).
b. Coil sensor failure will initiate a Timed Limp
Mode. This will be accompanied by a 2 flash.
The DFC will initiate defrost after 60 minutes of
accumulated heating runtime and terminate
after a 5 minute defrost. The limp mode will
clear after the sensor fault is cleared.
c. Ambient sensor failure will initiate an Adaptive
Timed Limp Mode. This will be accompanied by
a 1 flash. The DFC will initiate defrost after 60
minutes of accumulated heating runtime and
force a defrost, which will terminate on coil
12
DEFROST
CONTROL
BEHAVIOR
5 flash goes away
after soft lockout
period expires. See
Note 2.
Heating short cycle
fault triggers 6 flash.
The system will follow
10 adaptive time
heating cycles and
then return to
demand defrost.
Outdoor temperature
is below -12°F. See
Note 5.
temp. The limp mode will clear after the sensor
fault is cleared.
d. This could be caused by a condenser fan motor
failure, low charge or other reasons.
3. The first 15 minute soft lockout the system will
return to normal operation. Should this continue to
operate in this manner there will be a 30 minute
soft lockout and so on. At the end of the lockout
process, if a hard lock is necessary, a 4 flash will be
announced and system operation is interrupted. If
the ambient temperature climbs above 40°F for
more than 30 minutes this clears this fault count
and resumes normal operation.
a. If or when normal operation is restored after the
ambient temperature climbs above 40°F for
more than 30 minutes and another LP trip is
monitored on the 9th trip this will initiate a hard
lockout that will not be cleared by temperature
or time.
4. Once ambient drops to -12 or lower wait 5 minutes
before soft lockout begins. During soft lockout the Y
signal passes through to the X2 output. Resume
operation when ambient temperature rises to -3°F
or higher and after 5 minute soft lockout period
expires. LPCO should reset around 5°F.
5. During a Hard Lockout, the X2 relay opens so that
the Y signal d d o o e e s s n n o o t t pass through.
LPCO
HEATING Mode
st
1 Trip 15 minute soft lock-out
nd
2 Trip
30 minute soft lock-out
rd
3 Trip 45 minutes soft lock-out
th th
4 – 8 Trip 18 hour soft lock-out
th
9 Trip (a)
(a) If LPCO is open, a 3 flash can accommodate any of the faults above
and will clear when the LPCO closes.
LPCO COOLING Mode
st
1 Trip 15 minute soft lock-out
nd
2 Trip 30 minute soft lock-out
rd
3 Trip 18 hour soft lock-out
th
4 Trip
18 hour soft lock-out
N N o o t t e e : : Once the LPCO closes, the 3 flash fault will not
continue showing – only 5 flash if in the soft-
lockout period.
Flash
Code
5 and 6 flash
period
5 and 6 flash
period
5 and 6 flash
period
5 and 6 flash
period
Hard lock-out 4 flash
Flash
Code
5 and 6 flash
period
5 and 6 flash
period
5 and 6 flash
period
4 flash
period
4TWL6036A-SF-1F-EN