This control shuts off gas control system and energizes
air-circulating blower motor if furnace overheats.
Recommended method of checking this 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 control has
shut off burners, return-air opening should be unblocked to
permit normal air circulation. By using this method to check
limit control, it can be established that limit is functioning
properly and operates if there is a restricted return-air supply
or motor failure. If limit control does not function during this
test, cause must be determined and corrected.
2. Check Pressure Switch
This control proves operation of draft inducer. Check switch
operation as follows:
a. Turn off 115-v power to furnace.
b. Remove outer furnace door and disconnect inducer motor
lead wires from wire harness.
c. Turn on 115-v power to furnace.
d. Set thermostat to
″
call for heat
″
and wait 1 minute. When
pressure switch is functioning properly, hot surface igniter
should not glow, and status code LED flashes a Status
Code 32. If hot surface ignitor glows when inducer motor
is disconnected, shut furnace down immediately. Deter-
mine reason pressure switch did not function properly and
correct condition.
e. Turn off 115-v power to furnace.
f. Reconnect inducer motor leads, reinstall main furnace door,
and turn on 115-v power supply.
CHECKLIST
1. Put away tools and instruments. Clean up debris.
2. Check SW-1 through SW-3 after completing installation to
ensure desired settings for thermostat type (SW-1) and
blower-OFF delay (SW-2 and SW-3).
3. Verify flame rollout manual reset switch has continuity.
4. Verify that blower and outer doors are properly installed.
5. Cycle test furnace with room thermostat.
6. Check operation of accessories per manufacturer’s instruc-
tions.
7. Review User’s Guide with owner.
8. Leave literature packet near furnace.
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