Controls User Manual
– Combo-pac
Rev_20 804 8 Page 7 of
cooling cycle. Default is 0 seconds. This can improve comfort by pre-cooling the AC coil.
Caution - excessive time may cause coil freeze-up.
PstCool – Length of time in seconds that the fan will run at half speed at the end of each
cooling cycle. Default is 30 seconds. This can improve efficiency by using residual cooling in
the AC coil.
PID_PROP, PID_INT, PID_DB, PID_RAMP – These settings are the proportional,
integral, deadband, and ramp rate used for the P.I.D. cooling speed control when in
auto mode. It is recommended that these settings only be changed by someone who
has a firm understanding of P.I.D. control schemes and only if the response rate of the
fan is unsatisfactory. Contact Vortex if you believe there’s an issue with these settings.
Two-Stage Air-Conditioning
An output is available on the low-voltage terminal strip for the control of a two-stage
air-conditioner. When a cooling call is present, the air conditioning compressor will
initially be activated in first stage (low). If the cooling call continues beyond time
AC2Time, second stage will be activated for the remainder of the cooling call. Note
that maximum and minimum airflows are automatically reduced to 2/3 during first
stage operation whether cooling is in fixed or auto mode.
AC_2STG – Turn ON if a 2-stage air conditioner is present.
AC2Time – The time, in minutes, in which 2nd stage is activated, set by default to
20 minutes. Decreasing this value will cause 2nd stage to be activated sooner,
leading to full capacity.
Freeze Protection
In order to prevent the heat exchanger coils from freezing during cooling, the air
handler includes a freeze protection feature. If the measured supply air temperature
drops below the freeze protection temperature FRZ_TMP, the signal to the air-
conditioner contactor is interrupted. In order to prevent short-cycling of the
compressor, this feature includes two settable delay intervals: FrzDly1 sets the amount
of time the supply air temperature has to remain below FRZ_TMP before the alarm is
triggered; and FrzDly2 sets the amount of time until the compressor is allowed to come
back on, once the supply air temperature has returned to above FRZ_TMP. Note: This
feature will only turn off the AC compressor signal. It will not protect the home or air
handler from freezing house temperatures or improper fresh air connections such as
from a heat recovery ventilator.
FRZ_TMP – The freeze protection setpoint temperature. Default value is 3 °C.
Lowering this value will decrease sensitivity of the freeze protection feature.
FrzDly1 – Amount of time (in minutes) to wait before acknowledging a freeze
protection condition. Default setting is 3 minutes. Increasing this value will decrease
