Carrier 59SP6A Installation, Start-Up, Operating, Service And Maintenance Instructions page 72

59SP6A: Installation, Start-up, Operating, Service and Maintenance Instructions
c. Two-Stage Thermostat and Two-Speed Cooling
See Fig. 39 and Fig. 40
NOTE: The air conditioning relay disable jumper ACRDJ must be
disconnected to allow thermostat control of the outdoor unit staging. See
Fig. 39.
The thermostat closes the R-to-G-and-Y1 circuits for low-cooling or
closes the R-to-G-and-Y1 and -Y2 circuits for high-cooling. The
R-to-Y1 circuit starts the outdoor unit on low-cooling speed, and the
R-to-G-and-Y1 circuit starts the furnace blower motor BLWM at
low-cooling airflow which is the true on-board CF (continuous fan)
selection as shown in Fig. 71. The R-to-Y1 and -Y2 circuits start the
outdoor unit on high-cooling speed, and the R-to-G-and-Y/Y2 circuits
start the furnace blower motor BLWM at high-cooling airflow.
High-cooling airflow is based on the A/C (air conditioning) selection
shown in Fig. 61.
The electronic air cleaner terminal EAC-1 is energized with 115 vac
whenever the blower motor BLWM is operating.
When the thermostat is satisfied, the R-to-G-and-Y1 or R-to- G-and-Y1
and -Y2 circuits are opened. The outdoor unit stops, and the furnace
blower BLWM and electronic air cleaner terminal EAC-1 will remain
energized for an additional 90 seconds. Jumper Y1 to DHUM to reduce
the cooling off-delay to 5 seconds. See
3. Dehumidification Mode
See Fig. 39 and Fig. 40 for thermostat connections.
The dehumidification output, D or DHUM on the Thermidistat
should be connected to the furnace control thermostat terminal
DHUM. When there is a dehumidify demand, the DHUM input is
activated, which means 24 vac signal is removed from the DHUM
input terminal. In other words, the DHUM input logic is reversed.
The DHUM input is turned ON when no dehumidify demand
exists. Once 24 vac is detected by the furnace control on the
DHUM input, dehumidification capability is activated. If the
DHUM input is removed for more than 48 hours, the furnace
control reverts back to non-dehumidification mode.
The cooling operation described in item 3 above also applies to
operation with a dehumidification thermostat. The exceptions are
listed below:
a. Low cooling-When the R-to-G-and-Y1 circuit is closed and
there is a demand for dehumidification, the low cooling airflow
demand is reduced by 10 percent.
b. High cooling-When the R-to-G-and Y/Y2 circuit is closed and
there is a demand for dehumidification, high cooling airflow
demand is reduced by 10 percent.
c. Cooling off-delay-When the "call for cooling" is satisfied and
there is a demand for dehumidification, the cooling blower-off
delay is decreased from 90 seconds to 5 seconds.
4. Continuous Blower Mode
When the R-to-G circuit is closed by the thermostat, the blower
motor BLWM will operate at continuous blower airflow.
Continuous blower airflow selection is initially based on the CF
(continuous fan) selection shown in
shown in Fig. 61. Terminal EAC-1 is energized as long as the
blower motor BLWM is energized.
During a call for heat, the furnace control CPU will transition the
blower motor BLWM to continuous blower airflow or heat airflow
whichever is lowest. The blower motor BLWM will remain ON
until the main burners ignite then shut OFF and remain OFF for the
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
for thermostat connections
Fig. 39.
Fig. 61. Factory default is
blower-ON delay (25 seconds in heat), allowing the furnace heat
exchangers to heat up more quickly, then restarts at the end of the
blower-ON delay period at heat airflow.
The blower motor BLWM will revert to continuous-blower airflow
after the heating cycle is completed.
When the thermostat "calls for low-cooling", the blower motor
BLWM will switch to operate at low-cooling airflow. When the
thermostat is satisfied, the blower motor BLWM will operate an
additional 90 seconds at low-cooling airflow before transitioning
back to continuous-blower airflow.
When the thermostat "calls for high-cooling", the blower motor
BLWM will operate at high cooling airflow. When the thermostat is
satisfied, the blower motor BLWM will operate an additional 90
seconds at high-cooling airflow before transitioning back to
continuous-blower airflow. When the R-to-G circuit is opened, the
blower motor BLWM will continue operating for an additional 5
seconds, if no other function requires blower motor BLWM
operation.
Continuous Blower Speed Selection from Thermostat
To select different continuous-blower airflow from the room thermostat,
momentarily turn off the FAN switch or push button on the room
thermostat for 1-3 seconds after the blower motor BLWM is operating.
The furnace control CPU will shift the continuous-blower airflow from
the factory setting to the next highest CF selection airflow as shown in
Fig. 61. Momentarily turning off the FAN switch again at the thermostat
will shift the continuous-blower airflow up one more increment. If you
repeat this procedure enough you will eventually shift the
continuous-blower airflow to the lowest CF selection as shown in
Fig. 61. The selection can be changed as many times as desired and is
stored in the memory to be automatically used following a power
interruption.
NOTE: If the blower-off delay is set to the maximum, the adjustable
continuous-fan feature is locked (i.e., fan speed cannot be changed from
its current setting).
5. Heat pump
See Fig. 39 and Fig. 40
When installed with a heat pump, the furnace control automatically
changes the timing sequence to avoid long blower off times during
demand defrost cycles. Whenever W is energized along with Y1 or
Y/Y2, the furnace control CPU will transition to or bring on the
blower motor BLWM at cooling airflow or low-heat airflow
whichever is lowest. The blower motor BLWM will remain on until
the main burners ignite then shut OFF and remain OFF for 25
seconds before coming back on at heating airflow. When the W/W1
input signal disappears, the furnace control begins a normal inducer
post-purge period while changing the blower airflow. If Y/Y2 input
is still energized the furnace control CPU will transition the blower
motor BLWM airflow to cooling airflow. If Y/Y2 input signal
disappears and the Y1 input is still energized the furnace control
CPU will transition the blower motor BLWM to low-cooling
airflow. If both the Y1 and Y/Y2 signals disappear at the same time,
the blower motor BLWM will remain on at low-heat airflow for the
selected blower-OFF delay period. At the end of the blower-OFF
delay, the blower motor BLWM will shut OFF unless G is still
energized, in which case the blower motor BLWM will operate at
continuous blower airflow.
72
for thermostat connections.