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C.
Evaporator Airflow and Airflow Adjustments
Table
5 shows
the
temperature
rise
at various
airflow
rates.
Tables
9 and
10 show
both
heating
and
cooling
airflows
at
various
external
static
pressures.
Refer
to these
tables
to de-
termine
the
airflow
for
the
system
being
installed.
See
Table
11 for wet
coil
pressure
drop.
NOTE: Be sure that all supply
and return-air
grilles are open,
free from obstructions,
and adjusted
properly.
Airflow can be changed
by changing
the lead connections
of
the blower
motor.
Unit PYIP
two- or 3-speed
motors
(except
size 030) are fac-
tory wired for low speed operation.
Unit PY1P is factory wired
for medium
speed.
For 208/230-v
and A.O. Smith
460-v Blower
Motors
The motor leads
are color-coded
as follows:
3 SPEED
2 SPEED
black
= high speed
black
= high speed
blue
= medium
speed
red
= low speed
red
= low speed
To change
the speed of the blower motor, remove
the fan mo-
tor speed
leg lead fl'om the blower
relay
(BR). This wire
is
attached
to terminal
BM for single-phase
and 3-phase
units.
To change
the speed,
remove
and replace
with
lead
for de-
sired blower motor speed.
In_sulare tire remowH
leaH m avoicl
c'onract with c'hassis /raz'r_s.
For 460-v GE Motors
The motor leads
are color coded as follows:
3 SPEED
2 SPEED
black
= high
black
= high
blue
= jumper
blue
= jumper
orange
= medium
red
= low
red
= low
To change
the speed
of the blower
motor, remove
fan motor
speed
lead from the blower
relay
(BR) and replace
with the
lead for the desired
blower motor speed. The motor speed lead
is attached
to terminal
BM. [n.sul_r_ remov_ct leact end ro avoid
contact
with c'ha.ssLs Darts. On 3-speed
motors
only, connect
orange
lead to terminal
BM of BR. To select high
speed
on
460 v GE motors,
separate
the black
(female
QC) fi'om the
blue lead (male QC) and connect
the black
lead to the BR.
[n_sulare tire blue leact go avoiH contact
with ar_y c'hasMs parr&
D. Cooling
Sequence
of Operation
With
the
room
thermostat
SYSTEM
switch
in the
COOL
po-
sition
and
the
FAN
switch
in the AUTO.
position,
the
cooling
sequence
of operation
is as follows:
When
the
room
temperature
rises
to a point
that
is slightly
above
the
cooling
control
setting
of the
thermostat,
the
ther
mostat
completes
the
circuit
between
thermostat
terminal
R
to terminals
Y and
G. These
completed
circuits
through
the
thermostat
connect
contactor
coil
(C) (through
unit
wire
Y)
and
blower
relay
coil
(BR)
(through
unit
wire
G) across
the
24 v secondary
of transformer
(TRAN).
The
normally-open
contacts
of energized
contactor
(C) close
and
complete
the
circuit
through
compressor
motor
(COMP)
to condenser
(outdoor)
fan
motor
(OFM).
Both
motors
start
instantly.
The
set of normally-open
contacts
of energized
relay
BR close
and
complete
the
circuit
through
evaporator
blower
(indoor)
fan motor
(IFM).
The
blower
motor
starts
instantly.
NOTE:
Once
the compressor
has started
and
then
has stopped,
it should
not be started
again
until
5 minutes
have
elapsed.
The
cooling
cycle
remains
"on" until
the
room
temperature
drops
to point
that
is slightly
below
the
cooling
control
set
ting
of the
room
thermostat.
At this
point,
the
thermostat
"breaks"
the
circuit
between
thermostat
terminal
R to termb
nals
Y and
G. These
open
circuits
deenergize
contactor
coil C
and
relay
coil BR. The condenser
and compressor
motors
stop.
After
a 30-second
delay,
the
blower
motor
stops.
The
unit
is
in a "standby"
condition,
waiting
for the
next
"call
for cool
ing" fl'om
the
room
thermostat.
24
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