b. After valve is found to operate satisfactorily, reconnect
thermocouple to gas valve (finger-tight position only).
c. Tighten thermocouple connection 1/4-turn with a wrench.
d. Relight the pilot following lighting instructions on furnace.
2. Check primary limit control.
This control shuts off the combustion control system and
energizes the circulating-air blower motor if the furnace
overheats.
The preferred method of checking the limit control is to
gradually block off the return air after the furnace has been
operating for a period of at least 5 minutes. As soon as the
limit has shut off the burners, the return-air opening should be
unblocked. By using this method to check the limit control, it
can be established that the limit is functioning properly and
will operate if there is a motor failure.
3. Check draft safeguard switch.
The purpose of this control is to permit the safe shutdown of
the furnace during certain blocked vent conditions.
a. Disconnect power to furnace and remove vent connector
from furnace outlet collar. Be sure to allow time for vent
pipe to cool down before removing.
b. Set room thermostat above room temperature and restore
power to furnace.
c. After normal start-up, allow furnace to operate for 2
minutes, then block 50 percent of flue outlet. Furnace
should cycle off within 3 minutes.
d. Remove blockage and reconnect vent pipe to furnace outlet
collar.
e. Wait 5 minutes and then reset draft safeguard switch.
4. Check pressure switch.
This control proves operation of draft inducer blower.
a. Turn off 115-v power to furnace.
b. Remove 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 the burners do not light, the pressure switch is function-
ing properly.
e. Turn off 115-v power to furnace.
f. Reconnect inducer motor wires, replace control door, and
turn on 115-v power.
CHECKLIST
1. Put away tools and instruments, and clean up debris.
2. Verify manual reset switches have continuity.
3. Ensure blower and control access doors are properly installed.
4. Cycletest furnace with room thermostat.
5. Check operation of accessories per manufacturer’s instruc-
tions.
6. Review User’s Manual with owner.
7. Leave literature packet near furnace.
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