5
Unitary Products Group
The electronic furnace control is
equipped with a diagnostic light which
flashes when there is a service prob-
lem. The diagnostic codes are:
Steady on Normal operation.
ONE flash: Ignition failure.
TWO flashes: Pressure switch failed
closed.
THREE flashes: Pressure switch
failed open.
FOUR flashes: Limit switch open.
FIVE flashes: Gas valve energized
with no call for heat
SIX flashes
or Rapid flash: Reversed polarity
If a problem is indicated, contact your
authorized service person.
THE FURNACE CONTROLS
AND THEIR FUNCTION
1. System Switch -- This system
switch turns ON or OFF the 120
volt electrical circuit that powers
the furnace controls and the
blower motor. The system switch
must be turned ON for the fur-
nace to operate. Turn the switch
to OFF when cleaning the blower,
etc. See Figure 2.
2. Limit Control -- This furnace is
protected by two high tempera-
ture safety limit switches. The
auxiliary (upper) limit switch and
the high temperature (lower) limit
switch are automatic reset types.
If either limit trips, the burner will
shut off. If either limit switch trips
off again soon after resetting, set
the furnace ON--OFF switch to
the “OFF” position and call your
authorized technician.
3. Gas Valve -- The gas valve for the
gas furnaces are a 100% shut--off
type and will fail safe if for some
reason the gas is turned off.
FIGURE 4 -- FURNACE CONTROLS
BLOWER
DIAGNOSTIC
LIGHT
COMBUSTION
FAN MOTOR
SYSTEM
SWITCH
BURNER
OBSERVATION
WINDOW
GAS VALVE
BURNER AIR
SHUTTER
ADJUSTMENT
ROD
LIMIT
SWITCH
UPPER
LIMIT
SWITCH
GENERAL INFORMATION FOR ALL MODELS
Gas Shutoff
Shouldoverheatingoccur, or the
gas supply fail to shut off, shut
off the manual gas valve to the
furnace and allow blower to run
until furnace cools down and
blower shuts off before shutting
off the electrical supply.
The furnace gas valve is equipped
with a manual gas shutoff. Figure 2
shows the location of the manual
shutoff valve. To turn off gas to the fur-
nace, move the lever on the gas valve
to the OFF position.
The furnace installation should also
have a manual shutoff valve in the
gas piping to the furnace, similar to
what is shown in Figure 5 . To turn off
the gas to the furnace, use a wrench
and turn the knob or lever so that it is
pointing 90 degrees from the gas
pipe, as shown in Figure 5.
OFF
ON
OFF
ON
FIGURE 5 -- MANUAL GAS
SHUTOFF VALVE
Set the room thermostat at the de-
sired room temperature. Greatest
comfort will be achieved when the
setting is not changed frequently.
For energy conservation and econ-
omy it is recommended that the ther-
mostat be set at 68_for heating and
80_for cooling.
For Heating with Air Conditioning
Applications -- Set HEAT/COOL
switch to HEAT position and set FAN
switch to AUTO position.
Observing Burner
Operation
1. Observe burner to make sure it
ignites. Observe color of flame.
On natural gas the flame will burn
blue with appreciably yellow tips.
On Propane gas a yellow flame
may be expected. If flame is not
the proper color call a qualified
serviceman for service. See Fig-
ure 6 and 7.
2. Let furnace heat until blower
cycles on.
3. Turn thermostat down.
4. Observe burner to make sure it
shuts off.
5. Let the furnace cool and blower
cycle off
If any abnormalities are observed
when checking for correct operation,
such as burner failing to ignite or to
turn off, sooty flame, etc., call your
nearest authorized service technician
as shown in the Service Center List
included in the home owner envelope.
