Nordyne Outdoor Heat Pump T3BN - Manual (Page 9)

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2. Jumper the “T2”-”DFT” test pins. This will
indicate to the board that the defrost T-stat
is closed(if the compressor is running).
Defrost T-stat is closed at 32° or below and
is open at 68° or above. But it’s state is
unknown if the temperature is between 32°F
and 68°F. The defrost thermostat tells the
board whether a defrost cycle needs to be
started or terminated. With the DFT closed
the unit will run for 30/60/90 minutes in heat
mode and then defrost the outdoor coil. The
defrost will turn off the outdoor fan, turn on the
compressor and raise the coil temperature to
68°F. This will open the DFT and terminate
the defrost. If the DFT does not open the
defrost will end after 10 minutes.
3. Defrost board speed-up. With compressor
running in heat mode, next jump the “Test”
pin to “C” on terminal strip. This will initiate
a defrost test in 5, 10 or 15 seconds (This
is determined by the 30, 60 or 90 minute
defrost pin settings. The factory setting will
be 30 minutes). Note that this will bypass the
compressor off delay when the unit goes into
defrost test and if left in defrost test, the delay
will be bypassed when the test is terminated
by the processor. If the jumper is removed
before the test is over the processor will
perform the remainder of a normal defrost.
See step 2 above.
4. Remove the jumpers.
Note: The delay/no-delay pin concerns
compressor operation during defrosts. The default
setting is delay. Reciprocating compressors
should only use this setting in conjunction with
an approved hard start kit. Scroll compressors
that have noise issues while going into or coming
out of defrost should use this 30 second delay to
reduce the defrost noise. To switch from no-delay
to delay remove the pin from the “no-delay” pin
location and shift it to the “delay” pin location.
Speed up changes:
Manually initiating a defrost will cause the
compressor to run continually when entering
defrost.
Normal defrost operation:
To test normal defrost operation when the
temperature is above 35°F, jumper “R” to
“DFT” on the 624656 board and allow the unit
to run for 30 minutes. Defrost will continue
until the “R” to “DFT” jumper is removed or
for 10 minutes. Remove the jumper.
The 5 minute time delay feature can be shortened
1 time to 1 second by jumping the “Test” to “C”
terminal. Remove the jumper and repeat as
desired.
Note: If jumper is left on the “Test” to “common”
pins permanently, the defrost cycle will become
inoperable.
Defrost Test Procedure for 624656
1. Jumper “T2” to “DFT” at the test terminals.
2. With unit running in heat mode, short the
“TEST” terminal to the common terminal near
it. This will speed up the board and cause
it to enter defrost mode in 5/10/15 seconds
depending on the defrost time selection.
Compressor delay will not function during
speed-up.
3. This test will end in 5 seconds if the “TEST”-
common short is not removed.
4. Remove both the short and the “T2” to “DFT”
jumper to terminate the defrost cycle. The
30 second compressor delay should operate
normally.
5. Test is complete, reset thermostat to home
owner preference.