Operating instructions

high heat, speed selection can be med-high, med (5-
speed blowers only), or med-low (factory setting). For
low heat, speed tap selection can be low (factory setting),
med-low, or med (5-speed blowers only).
WARNING: Disconnect electrical power before chang-
ing speed tap (or removing cap on 5-speed motors). A
failure to follow this warning can cause personal injury or
death.
NOTE: For furnaces with 5-speed motors, ensure that unused
speed tap is capped before power is restored.
d. To change motor speed selection for high heat, remove
blower motor lead from control HIGH-GAS-HEAT
terminal. (See Fig. 14 and Fig. 18.) Select desired blower
motor speed lead from 1 of the other terminals and
relocate it to HIGH-GAS-HEAT terminal. See Table 12
for lead color identification. Reconnect original lead to
PARK terminal (or cover with insulating cap, applies
only to furnaces with 5-speed blower motors). Follow
this same procedure for proper selection of cool and
low-gas-heat speed selection.
3. Set thermostat heat anticipator.
a. When using a nonelectronic thermostat, the thermostat
heat anticipation must be set to match amp draw of
electrical components in R-W/W1 circuit. Accurate amp
draw readings can be obtained at wires normally con-
nected to thermostat subbase terminals R and W/W1.
Fig. 21 illustrates an easy method of obtaining actual
amp draw. The amp reading should be taken after blower
motor has started and furnace is operating in low heat.
To operate furnace in low heat, first move SW-2 to ON
position, THEN connect ammeter wires as shown in Fig.
21. The thermostat anticipator should NOT be in this
circuit while measuring current. If thermostat has no
subbase, thermostat MUST be disconnected from R and
W/W1 wires during current measurement. Return SW-2
to final desired location after completing reading. See
thermostat manufacturer’s instructions for adjusting heat
anticipator and for varying heating cycle length.
b. When using an electronic thermostat, set cycle rate for 3
cycles per hr.
E. Check Safety Controls
The flame sensor, gas valve, and pressure switches were all
checked in the Start-Up section as part of normal operation.
1. Check primary limit control.
This control shuts off combustion control system and
energizes circulating-air blower motor if furnace overheats.
The preferred method of checking limit control is to
gradually block off return air after furnace has been
operating for a period of at least 5 minutes. As soon as limit
has shut off burners, return-air opening should be un-
blocked. By using this method to check limit control, it can
be established that the limit is functioning properly and will
operate if there is a motor failure.
2. Check draft safeguard switch.
The purpose of this control is to permit safe shutdown of he
furnace during certain blocked vent conditions.
a. Disconnect power to furnace and remove vent connector
from furnace flue collar. Be sure to allow time for vent
connector pipe to cool down before removing.
b. Restore power to furnace and set room thermostat above
room temperature.
c. After normal start-up, allow furnace to operate for 2
minutes, then block flue outlet 100 percent. Furnace
should cycle off within 2 minutes.
d. Remove blockage and reconnect vent connector to
furnace flue collar.
e. Wait 5 minutes and then reset draft safeguard switch.
3. Check flow-sensing pressure switches.
This control proves operation of draft inducer blower.
a. Turn off 115-v power to furnace.
b. Remove gas control door and disconnect inducer motor
lead wires from wire harness.
c. Turn on 115-v power to furnace
d. Close thermostat switch as if making normal furnace
start. If hot surface ignitor does not glow within several
minutes and control flashes code 32, pressure switches
are functioning properly.
e. Turn off 115-v power to furnace.
f. Reconnect inducer motor wires, replace gas control door,
and turn on 115-v power to furnace.
4. Check auxiliary limits.
a. Turn off 115-v power to furnace.
TABLE 12—SPEED SELECTION
COLOR SPEED AS SHIPPED
White Common C
OM
Black High Cool
Orange† Med Capped
Yellow Med-High Park
Blue Med-Low High-Gas-Heat
Red Low* Low-Gas-Heat
* Continuous fan speed.
† Available on 5-speed blowers only.
CAUTION: Recheck temperature rise. It must be within
limits specified on unit rating plate. Recommended op-
eration is at midpoint of rise range or above.
Fig. 21—Amp Draw Check With Ammeter
A96316
R Y W G
10 TURNS
THERMOSTAT SUBBASE
TERMINALS WITH
THERMOSTAT REMOVED
(ANITICIPATOR, CLOCK, ETC.,
MUST BE OUT OF CIRCUIT.)
HOOK-AROUND
AMMETER
EXAMPLE:
5.0 AMPS ON AMMETER
10 TURNS AROUND JAWS
=
0.5 AMPS FOR THERMOSTAT
ANTICIPATOR SETTING
FROM UNIT 24-V
CONTROL TERMINALS
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