Tempstar A Series, Installation, Start-Up, Operating, Service And Maintenance Instructions

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F96CTN and G96CTN (Series A): Installation, Start-up, Operating, Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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circuits always causes high-heat operation, regardless of the setting of
the low-heat only switch.
The wall thermostat “calls for heat”, closing the R-to-W1 circuit for
low-heat or closing the R-to-W1-and-W2 circuits for high-heat. The
furnace control performs a self-check, verifies the low-heat and
high-heat pressure switch contacts LPS and HPS are open, and starts the
inducer motor IDM in high-speed.
The start up and shut down functions and delays described in item 1.
above apply to the 2-stage heating mode as well, except for switching
from low- to high-Heat and vice versa.
a. Switching from Low- to High-Heat - If the thermostat R-to-W1
circuit is closed and the R-to-W2 circuit closes, the furnace
control CPU will switch the inducer motor IDM speed from low
to high. The high-heat pressure switch relay HPSR is
de-energized to close the NC contact. When sufficient pressure is
available the high-heat pressure switch HPS closes, and the
high-heat gas valve solenoid GV-HI is energized. The blower
motor BLWM will transition to high-heat airflow five sec after
the R-to-W2 circuit closes.
b. Switching from High- to Low-Heat -If the thermostat R-to- W2
circuit opens, and the R-to-W1 circuit remains closed, the
furnace control CPU will switch the inducer motor IDM speed
from high to low. The high-heat pressure switch relay HPSR is
energized to open the NC contact and de-energize the high-heat
gas valve solenoid GV-HI. When the inducer motor IDM reduces
pressure sufficiently, the high-heat pressure switch HPS will
open. The gas 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. 38 and Fig. 39 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. 60 .
The electronic air cleaner terminal EAC-1 is energized with 115
vac when the blower motor BLWM is operating.
When the thermostat is satisfied, the R-to-G-and-Y circuits are
opened. The outdoor unit will stop, and the furnace blower motor
BLWM will continue operating at cooling airflow for an
additional 90 sec. Jumper Y/Y2 to DHUM to reduce the cooling
off-delay to 5 sec. See Fig. 38 .
b. Two-Stage Thermostat and Two-Speed Cooling
See Fig. 38 and Fig. 39 for thermostat connections
NOTE: The air conditioning relay disable jumper ACRDJ must be
disconnected to allow thermostat control of the outdoor unit staging. See
Fig. 38 .
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. 60 . 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. 60 .
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 sec. Jumper Y1 to DHUM to
reduce the cooling off-delay to 5 sec. See Fig. 38 .
4. Dehumidification Mode
See Fig. 38 and Fig. 39 for thermostat connections.
The dehumidification output, D or DHUM on the Thermostat
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, the furnace control 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 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. 60 .
b. High cooling -When the R-to-G-and Y/Y2 circuit is closed and
there is a demand for dehumidification, the furnace 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. 60 .
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 Dehumidify mode and there is a demand for
dehumidification. The cooling operation described in item 3 above
also applies to operation with a dehumidification 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 furnace 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 closes or the demand for dehumidification is
satisfied. Low-cooling airflow is the true on-board CF
(continuous fan) selection as shown in Fig. 60 .
b. When the R-to-Y/Y2 circuit is closed, R-to-G circuit is open, and
there is a demand for dehumidification, the furnace 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 closes or the demand for
dehumidification is satisfied. High-cooling airflow is based on
the A/C (air conditioning) selection shown in Fig. 60 .
c. 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.
6.
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 Fig. 60 . Factory default is
shown in Fig. 60 . 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, low-heat
airflow, or the mid-range airflow, whichever is lowest. The blower
motor BLWM will remain ON until the main burners ignite then