1. 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.
2. Check draft safeguard switch. (Category I vent installation.)
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.
Fig. 15—Amp Draw Check With Ammeter
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 pipe to furnace outlet
collar.
e. Wait 5 minutes and then reset draft safeguard switch.
3. Check flow-sensing 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 hot surface ignitor does not glow within several
minutes and control flashes code 32, then the flow-sensing
switch is functioning properly.
e. Turn off 115-v power to furnace.
f. Reconnect inducer motor wires, replace control door, and
turn on 115-v power.
CHECK LIST
1. Put away tools, instruments, and clean up debris.
2. Check SWl through SW4 after completing installation to
ensure desired settings for thermostat type (SWl and SW2)
and blower off delay (SW3 and SW4).
3. Verify manual reset switches have continuity.
4. Ensure blower and control access 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 Manual with owner.
8. Leave literature packet near furnace.
Copyright 1993 CARRIER Corp. • 7310 W. Morris St. • Indianapolis, IN 46231 15090c
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
BookI 1 I 4 PC 101 Catalog No. 565-896 Printed in U.S.A. Form 58TUA-1SI Pg 18 8-93 Replaces: New
Tab [6a|8a
(13 pages)
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