Daikin DAR09 Service Instructions Manual page 49

SYSTEM OPERATION
AFE18-60A Control Board
Description
The AFE18 control is designed for use in heat pump applications
where the indoor coil is located above/downstream of a gas or
fossil fuel furnace. It will operate with single and two stage heat
pumps and single and two stage furnaces. The AFE18 control
will turn the heat pump unit off when the furnace is turned on.
An anti-short cycle feature is also incorporated which initiates
a 3 minute timed off delay when the compressor goes off. On
initial power up or loss and restoration of power, this 3 min-
ute timed off delay will be initiated. The compressor won't be
allowed to restart until the 3 minute off delay has expired. Also
included is a 5 second de-bounce feature on the "Y, E, W1 and
O" thermostat inputs. These thermostat inputs must be present
for 5 seconds before the AFE18 control will respond to it.
An optional outdoor thermostat, OT18-60A, can be used with
the AFE18 to switch from heat pump operation to furnace
operation below a specific ambient temperature setting, i.e.
break even temperature during heating. When used in this
manner, the "Y" heat demand is switched to the "W1" input to
the furnace by the outdoor thermostat and the furnace is used
to satisfy the first
stage "Y" heat demand. On some controls, if the outdoor ther-
mostat fails closed in this position during the heating season,
it will turn on the furnace during the cooling season on a "Y"
cooling demand. In this situation, the furnace produces heat
and increases the indoor temperature thereby never satisfying
the cooling demand. The furnace will continue to operate and
can only be stopped by switching the thermostat to the off
position or removing power to the unit and then replacing the
outdoor thermostat. When the AFE18 receives a "Y" and "O"
input from the indoor thermostat, it recognizes this as a cooling
demand in the cooling mode. If the outdoor thermostat is stuck
in the closed position switching the "Y" demand to the "W1"
furnace input during the cooling mode as described above, the
AFE18 won't allow the furnace to operate. The outdoor ther-
mostat will have to be replaced to restore the unit to normal
operation.
HIGH VOLTAGE!
Disconnect ALL power before servicing
or installing. Multiple power sources
may be present. Failure to do so may
cause property damage, personal injury
or death.
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