Installation Manual

86 440 01 4900 00
Specifications subject to change without notice.
valve solenoid GV -- M will remain energized as long as the
low--heat pressure switch LPS remains closed. The blower
motor BLWM will transition to low--heat airflow five sec
after the R--to--W2 circuit opens.
3. Cooling mode
The thermostat “calls for cooling”.
a. Single--Speed Cooling --
See Fig. 37 and 38 for thermostat connections
The thermostat closes the R-- to--G--and--Y circuits. The
R--to-- Y circuit starts the outdoor unit, and the R-- to--
G--and--Y/Y2 circuits start the furnace blower motor
BLWM on cooling airflow. Cooling airflow is based on the
A/C selection shown in Fig. 64. The electronic air cleaner
terminal EAC--1 is energized with 115 vac when the blow-
er motor BLWM is operating.
When the thermostat is satisfied, the R--to--G--and--Y cir-
cuits are opened. The outdoor unit will stop, and the fur-
nace blower motor BLWM will continue operating at cool-
ing airflow for an additional 90 sec. Jumper Y/Y2 to
DHUM to reduce the cooling off--delay to 5 sec. See Fig.
37.
b. Two-- Stage Thermosta t and Two -- Speed Cooling
See Fig. 37 and 38 for thermostat connections
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. 64.
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)
selectionshowninFig.64.
The electronic air cleaner terminal EAC--1 is ener gized 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 BL WM and electronic air cleaner terminal
EAC--1 will remain ener gized for an additional 90 sec. Jumper Y1
to DHUM to reduce the cooling off--delay to 5 sec. See Fig. 37 .
4. Dehumidification Mode
See Fig. 37 and 38 for thermostat connections.
The dehumidification output, D or DHUM on the Th ermo-
stat should be connected to the furnace control thermostat
terminal DHUM. When there is a dehumidify d emand, the
DHUM input is activated, which means 24 vac signal is re-
moved 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 de-
tected by the furnace control on the DHUM input, the fur-
nace control dehumidification capability is activated. If the
DHUM input is removed for more than 48 hours, the fur-
nace control reverts back to non --dehumidification mode.
The cooling operation described in item 3. above also ap-
plies to operation with a dehumidification thermostat. The
exceptions are listed below:
a. Low cooling-- W h e n t h e R -- t o -- G -- a n d -- Y 1 c i r c u i t i s c l o s e d
and there is a demand for dehumidification, the furnace
blower motor BLWM will drop the blower airflow to 86
percent of low--cooling airflow which is the true on--board
CF (continuous fan) selection as shown in Fig. 64.
b. High cooling-- W h e n t h e R -- t o -- G -- a n d Y / Y 2 c i r c u i t i s
closed and there is a demand for dehumidification, the fur-
nace blower motor BLWM will drop the blower airflow to
86 percent of high--cooling airflow. High--cooling airflow
is based on the A/C (air conditioning) selection shown in
Fig. 64.
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 sec to 5 sec.
5. Super-- Dehumidify Mode
Super--Dehumidify mode can only be entered if the furnace
control is in the Thermidistat mode and there is a demand
for dehumidification. The cooling operation described in
item 3 above also applies to operation with a dehumidifica-
tion thermostat. The exceptions are listed below:
a. When the R--to--Y1 circuit is closed, R--to--G circuit is
open, and there is a demand for dehumidification, the fur-
nace blower motor BLWM will drop the blower airflow to
65 percent of low--cooling airflow for a maximum of 10
minutes each cooling cycle or until the R--to--G circuit clos-
es or the demand for dehumidification is satisfied. Low--
cooling airflow is the true on--board CF (continuous fan)
selectionasshowninFig.64.
b. When the R--to--Y/Y2 circuit is closed, R --to--G circuit is
open, and there is a demand for dehumidification, the fur-
nace blower motor BLWM will drop the blower airflow to
65 percent of high-- cooling airflow for a maximum of 10
minutes each cooling cycle or until the R--to--G circuit clos-
es or the demand for dehumidification is satisfied. High--
cooling airflow is based on the A/C (air conditioning) se-
lectionshowninFig.64.
c. When the “call for cooling” is satisfied and there is a de-
mand for dehumidification, the cooling blower--off delay
is decreased from 90 sec to 5 sec.
6. Continuous Blower Mode
When the R--to--G circuit is closed by the thermostat, the
blower motor BLWM will operate at continuous blower air-
flow. Continuous blower airflow selection is initially based
on the CF (continuous fan) selection shown in Fig. 64. Fac-
tory default is shown in Fig. 64. Terminal EAC --1 is ener-
gized as long as the blower motor BLWM is energized.
During a call for heat, the furnace control CPU will transi-
tion the blower motor BLWM to continuous blower airflow,
low--heat airflow , or the mid--range airflow, whichever is
lowest. The blower motor BLWM will remain ON until the
main burners ignite then shut OFF and remain OFF for the
blower-- ON delay (45 sec in low--heat, and 25 sec in high --
heat), allowing the furnace heat exchangers to heat up more
quickly, then restarts at the end of the blower --ON delay pe-
riod at low--heat or high--heat airflow, respectively .
The blower motor BLWM will revert to continuous--blower
airflow after the heating cycle is completed. In high--heat,
the furnace control CPU will drop the blower motor BLWM
to low--heat airflow during the selected blower--OFF delay
period before transitioning to continuous--blower airflow.
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 sec at low--cooling airflow be-
fore 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 op-
erate an additional 90 sec 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 sec, if no other func-
tion requires blower motor BLWM operation.
7. Heat pump
See Fig. 37 and 38 for thermostat connections.
When installed with a heat pump, the furnace control auto-
matically changes the timing sequence to avoid long blower
off times during demand defrost cycles. Whenever W/W1 is
energized along with Y1 or Y/Y2, the furnace control CPU