Bryant 312AAV User Manual

Page 18

The thermostat closes the R-to-G-and-Y1 circuits for
low-cooling or closes the R-to-G-and-Y1-and-Y2 cir-
cuits 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
on low-cool speed (same speed as LO-HEAT). 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 on COOL speed.
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 Fig. 22.)

NOTE: The air conditioning relay disable jumper ACRDJ must

be disconnected to allow thermostat control of the outdoor unit

staging. (See Fig. 22.)

4. Thermidistat Mode

(See Fig. 24, 25, 26, and 27 for Thermidistat connections)

The dehumidification output, 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,

the furnace control operates in Thermidistat mode. If the

DHUM input is off for more than 48 hours, the furnace

control reverts back to non-Thermidistat mode.

The cooling operation described in item 3 above also

applies to operation with a Thermidistat. The exceptions are

listed below:

a. When the R-to-G-and-Y1 circuit is closed and there is a

demand for dehumidification, the furnace blower motor
BLWM will continue running at low-cool speed (same
speed as LO-HEAT).

b. 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 speed from COOL to
HI-HEAT for a maximum of 10 minutes before reverting
back to COOL speed. If there is still a demand for
dehumidification after 20 minutes, the furnace control
CPU will drop the blower speed back to HI-HEAT
speed. This alternating 10-minute cycle will continue as
long as there is a call for cooling.

c. 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.

5. Continuous Blower Mode

When the R-to-G circuit is closed by the thermostat, the
blower motor BLWM will operate on continuous-blower
speed (can be set to LO-HEAT, HI-HEAT, or COOL
speed). Factory default is LO-HEAT speed. Terminal
EAC-1 is energized as long as the blower motor BLWM is
energized.
During a call for heat, the blower BLWM will stop during
igniter warm-up (17 seconds), ignition, and blower-ON
delay (45 seconds in low-heat, and 25 seconds in high-heat),
allowing the furnace heat exchangers to heat up more
quickly, then restarts at the end of the blower-ON delay
period at LO HEAT or HI HEAT speed.
The blower motor BLWM will revert to continuous-blower
speed after the heating cycle is completed. In high-heat, the

Fig. 22–Furnace Control

A00380

LHT

OFF

DLY

OFF

BLW

24-V-THERMOSTAT

TERMINALS

SETUP SWITCHES

LOW-HEAT ONLY AND

BLOWER OFF-DELAY

TWINNING AND/OR

COMPONENT TEST

TERMINAL

ACRDJ - AIR CONDITIONING

RELAY DISABLE JUMPER

TRANSFORMER 24-VAC

CONNECTIONS

PL1 - LOW VOLTAGE MAIN

HARNESS CONNECTOR

PL3 - ICM CONTROL

HARNESS CONNECTOR

HUMIDIFIER TERMINAL

(24-VAC 0.5 AMP MAX.)

3-AMP FUSE

LED OPERATION &

DIAGNOSTIC LIGHT

115-VAC (L2) NEUTRAL

CONNECTIONS

PL2 - HOT SURFACE

IGNITER & INDUCER

MOTOR CONNECTOR

115-VAC (L1) LINE

VOLTAGE CONNECTION

EAC-1 TERMINAL

(115-VAC 1.0 AMP MAX.)

BLOWER SPEED

SELECTION TERMINALS

HI HEAT

LO HEAT

SPARE-1

SPARE-2 COOL

Y1
DHUM

G
COM

24V

WW1

Y/Y2

TEST/TWIN

HUM

1 2 3

CRDJ

0.5-AMP024 VAC

FUSE 3-AMP

SEC-1

SEC-2

PL1

NEUTRAL-L2

EAC-2

BHT/CLR

BHI/LOR

PL3 1

BLWR

COOL

SPARE-1

SPARE-2

1-AMP@115 VAC

EAC-1

PR-1

IDR

HSIR

IDM

IHI/LOR

PL2

HSI HI LO

STATU

COD

HI HEA

LO HEA

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