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Bryant 313AAV User Manual

Page 51

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51

5. Heat pump

(See Fig. 25 -- 32 for thermostat connections.) When

installed with a heat pump, the furnace control
automatically changes the timing sequence to avoid long
blower off times during demand defrost cycles. When the

R--to-- W--and--Y1 or R--to--W--and--Y1--and--G circuits
are energized the furnace control CPU will switch to or

turn on the blower motor BLWM at HEAT speed, and
begin a heating cycle. The blower motor BLWM will
remain on until the end of the prepurge period, then shut

off for 24 seconds then come back on at HEAT speed.
When the W input signal disappears, the furnace control

begins a normal inducer post--purge period and the blower
remains running at HEAT speed for the selected
blower--OFF delay period then switches to low--cool

speed

(same

speed

as

FAN).

If

the

R--to--W--and--Y1--and--G signals disappear at the same

time, the blower motor BLWM will remain on for the
selected blower--OFF delay period. If the R--to--

W--and--Y1 signals disappear, leaving the G signal, the
blower motor BLWM will remain on for the selected
blower--OFF

delay

period

then

switch

to

continuous--blower speed. When the R--to--W--and--Y/Y2,
R--to--W--and--Y/Y2--and--G,

R--to--W--and--Y1--and--

Y/Y2, or R--to--W-- and--Y1--and--Y/Y2--and--G circuits
are energized the furnace control CPU will switch to or

turn on the blower motor BLWM at HEAT speed, and
begin a heating cycle. The blower motor BLWM will

remain on until the end of the prepurge period, then shut
off for 24 seconds then come back on at HEAT speed.
When theWinput signal disappears, the furnace control

begins a normal inducer post--purge period and the blower
switches to COOL speed after a 3 second delay. If the

R--to--W--and--Y/Y2--and--G or R--to--W--and--Y1--and --
Y/Y2--and--G signals disappear at the same time, the
blower motor BLWM will remain on for the selected

blower--OFF delay period. If the R--to--W--and--Y/Y2 or
R--to--W--and--Y1--and--Y/Y2 signals disappear, leaving

the G signal, the blower motor BLWM will remain on for
the selected blower--OFF delay period then switch to
continuous blower speed.

Wiring Diagrams
Refer to Fig. 59 for wiring diagram.
Troubleshooting
Refer to the service label. (See Fig. 55.) The Troubleshooting

Guide (See Fig. 60) can be a useful tool in isolating furnace
operation problems. Beginning with the word “Start,” answer

each question and follow the appropriate arrow to the next item.

The Guide will help to identify the problem or failed component.
After replacing any component, verify correct operation

sequence.

313A