035-17468-001 Rev. A (801)
Unitary Products Group
37
INSTALLATION OF PSC MOTOR
1.
Install the PSC direct drive motor into motor mount.
2.
Slide motor in motor mount insuring there is no interfer-
ence between moving and stationary parts. Position wire
leads downward. Tighten motor mount band screw to 30
in. lbs.
3.
Center the blower wheel in the blower housing and align
the shaft flat with the blower wheel set screw. Tighten set
screw to 30 in. lbs.
4.
Replace blower assembly and fasten with 5 screws
5.
Strap motor capacitor to electric panel. Refer to Table 11
on page 37, for proper capacitor selection.
6.
Fasten electric panel to blower housing.
7.
Remove red wire from Circ. input terminal. Plug jumper
wire (attach to motor power harness) on 120 volt line ter-
minal on ignition control and jumper to Circ. Input. Con-
nect brown door switch wire to jumper.
8.
Connect white main harness lead to Line neutral.
9.
Connect motor leads to cool, heat lo and heat high per
electrical wire diagram table in the Installation manual.
10. Connect brown capacitor leads from motor to capacitor
and cover terminals with boot supplied.
FURNACE CONTROL DIAGNOSTICS
The furnace has built-in, self diagnostic capability. If a system
problem occurs, a fault code is shown by a blinking LED. It is
located behind a clear view port in the blower compartment
door. DO NOT remove the furnace blower compartment
panel OR turn off furnace power as either action will clear the
control's memory of the fault.
The control continuously monitors its own operation and the
operation of the system. If a failure occurs, the LED will indi-
cate the failure code. If the failure is internal to the control, the
light will stay on continuously. In this case, the entire control
should be replaced as the control is not field repairable.
If the sensed failure is in the system (external to the control),
the LED will flash in the following flash-pause sequences to
indicate failure status.
Flash sequence codes 1 thru 4 are as follows. LED will turn
on for 1/4 second and off for 1/4 second. This pattern will be
repeated the number of times equal to the code. For exam-
ple, two on flashes equals a number 2" fault code.
All flash code sequences are broken by a 2 second off period.
CONTINUOUS FLASH (1 sec on - 1 sec off):
This indi-
cates that flame was sensed when there was not a call for
heat. With this fault code the control will also turn on both the
inducer motor and supply air blower. This fault would typically
be caused by a gas valve that leaks through or is slow clos-
ing.
2 FLASH:
This indicates that the normally open pressure
switch contacts are stuck in the closed position. The control
confirms these contacts are open at the beginning of each
heat cycle. This would indicate a faulty pressure switch or
mis-wiring.
POWER SUPPLY POLARITY - Ignition Control
If the power supply polarity is reversed, the following unit
operation will occur. On a call for heat, the inducer will run,
the HSI will glow and the gas valve will energize and the
burners will ignite. The burners will immediately extinguish
and the unit will recycle. This will occur 3 times and then
the unit will lockout. A “7” flash code will be displayed. This
code means the flame could not be established. This
occurs because the control cannot sense flame with the
power supply polarity reversed.
Table 11:
PSC MOTOR SELECTION
UPFLOW MODELS
Model Number
Motor Part Number
Motor Horsepower
Capacitor Part Number
Capacitor Rating MF
60 / 55 / 1200 / B
024-23271-000
1/2
024-20045-000
7.5
80 / 75 / 1600 / C
024-26002-000
3/4
024-20046-000
10.0
100 / 95 / 2000 / C
024-23288-001
1
024-20446-000
15.0
120 / 112 / 2000 / D
024-23238-001
1
024-20446-000
15.0
DOWNFLOW/HORIZONTAL MODELS
Model Number
Motor Part Number
Motor Horsepower
Capacitor Part Number
Capacitor Rating MF
80 / 75 / 1200 / B
024-23271-000
1/2
024-20045-000
7.5
120 / 112 / 2000 / D
024-23238-001
1
024-20446-000
15.0
IGNITION CONTROL (P/N 031-01909-000)
Normal flame sense current is approximately
2.4 microamps DC (
µ
a)
Low flame signal control lockout point is
0.15 microamps (DC (
µ
a)