OM 931-6 • MicroTech III Unit Controller for WSHP
8
www.DaikinApplied.com
Control Outputs {A and IV/PR (H8)}
The control outputs are Alarm Fault (A) and Isolation
Valve / Pump Request {IV/PR (H8)}. The operation of the
control outputs during occupied mode is as follows:
• When JP4 is open the (A) terminal will be energized,
when there is no fault.
• When JP4 is shorted the (A) terminal is de-
energized, when there is no fault.
• Isolation Valve / Pump Request {IV/PR (H8)}: is
selectable to be energized when the compressor
is off (normally closed), or when the compressor is
on (normally open), by moving the wire lead to the
appropriate terminal.
Figure 3: H8 Terminals on MicroTech III Board
Fan Operation
The G terminal controls continuous fan operation. The
fan runs continuously when the G terminal is energized,
when not in unoccupied mode. When the G terminal is
de-energized, the fan cycles with the compressor.
Cooling Mode
The Y1 terminal controls the Cooling Mode of operation.
When the Y1 terminal is energized (24VAC), the
following occurs:
1 .
The fan energizes.
2 .
The IV/PR (H8) control output de-energizes or
energizes depending on the H8 terminal wiring (refer
to Figure 3).
3 .
The compressor energizes after 45 seconds.
4 .
If the reversing valve output is energized, the
reversing valve output will be de-energized 5
seconds after the compressor has been energized.
When the Y1 terminal is de-energized, the following
occurs:
1 .
The compressor de-energizes.
2 .
The fan de-energizes, unless the G terminal is
energized (24VAC), or JP2 is open.
3 .
The IV/PR (H8) control output energizes or de-
energizes depending on the H8 terminal wiring (refer
to Figure 3).
4 .
The reversing valve output remains de-energized.
Note:
To prevent compressor cycling, the default
minimum on time default is 180 seconds and
the minimum off time is 360 seconds. This may
cause the compressor time delay to be longer
than indicated above.
Heating Mode
The W1 terminal controls the occupied Heating Mode
of operation. When the W1 terminal is energized, the
following occurs:
1 .
The fan energizes
2 .
The IV/PR (H8) control output de-energizes or
energizes depending on the H8 terminal wiring (refer
to Figure 3).
3 .
The compressor energizes after 45 seconds.
4 .
If the reversing valve output is de-energized, the
reversing valve output will be energized 5 seconds
after the compressor has been energized.
When the W1 terminal is de-energized, the following
occurs:
1 .
The compressor de-energizes.
2 .
The fan de-energizes, unless the G terminal is
energized, or JP2 is open.
3 .
The IV/PR (H8) control output energizes or de-
energizes depending on H8 terminal wiring (refer to
Figure 3).
4 .
The reversing valve output remains energized.
Note:
To prevent compressor cycling, the default
minimum on time default is 180 seconds and
the minimum off time is 360 seconds. This may
cause the compressor time delay to be longer
than indicated above.
M
ICro
t
eCh
III u
nIt
C
ontroller
