HP - B 8
Control Boards
The outdoor fan motor connects to the control board
on Plug J3. During defrost, the motor is off. Service
Facts shipped with the outdoor unit contains a table of
PWM voltage requirements that can be checked to
determine if the control board is sending proper volt-
age to the fan motor (see tables below).
16 Seer Out Door Fan Motors
20 Seer Out Door Fan Motors
Terminate Temps
If the outdoor air temperature is above 6F, the maxi-
mum time in defrost is 15 minutes. If a defrost cycle
does not terminate within this time, the defrost will
terminate automatically. At temperatures 6F or below,
the maximum time in defrost is 12 minutes.
Fault LED
First Defrost Event
After system power up and 30 minutes in accumu-
lated heat mode operation, the integrated control board
will initiate a learning routine defrost cycle. The inte-
grated control will learn optimum defrost conditions
during this routine. The learning routine defrost cycle
will terminate on coil temperature or maximum over
ride time.
Conditions required for a defrost cycle to be permit-
ted:
The outdoor air temperature must be equal to or less
than 52F and the coil temperature must be 34.5F or
less to permit a defrost cycle.
To initiate defrost, the temperature difference between
outdoor coil and ambient sensors must be 1.9 times
greater than the difference in temperature between a
clean outdoor coil and ambient sensor. (As determined
after the learning routine).
Figure 14
Forcing a Defrost Cycle and
Speeding Up Defrost Timing
The control board features a test pin that can be jumped
to force the system into a defrost cycle when in heat
mode and to speed up defrost cycle timing during test-
ing.
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