Checklist - Carrier N8MXL Installation Instructions Manual

2. Check draft safeguard switch.
The purpose of this control is to cause the safe shutdown
of the furnace during certain blocked vent conditions.
a. Verify vent pipe is cool to the touch.
b. Disconnect power to furnace and remove vent connector
from furnace vent elbow.
c. Restore power to furnace and set room thermostat above
room temperature.
d. After normal start−up, allow furnace to operate for 2 min-
utes, then block vent elbow in furnace 80 percent of vent
area with a piece of flat sheet metal.
e. Furnace should cycle off within 2 minutes. If gas does not
shut off within 2 minutes, determine reason draft safe-
guard switch did not function properly and correct condi-
tion.
f. Remove blockage from furnace vent elbow.
g. Switch will auto−reset when it cools.
h. Re−install vent connector.
NOTE: Should switch remain open longer than 3 minutes,
furnace control board will lockout the furnace for 3 hours. To
reset furnace control board, turn thermostat below room
temperature or from HEAT to OFF and turn 115v power OFF,
then back ON.
3. Check Pressure Switch
This control proves operation of the draft inducer blower.
a. Turn off 115−v power to furnace.
b. 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 ignit-
er should NOT glow and control flashes a status code 3.
If hot surface igniter glows when inducer motor is discon-
nected, shut down furnace immediately.
e. Determine reason pressure switch did not function prop-
erly and correct condition.
f. Turn off 115−v power to furnace.
g. Reconnect inducer motor wires, replace outer door, and
turn on 115−v power.
h. Blower will run for 90 sec and flash status code 1+2 be-
fore beginning the call for heat again.
i. Furnace should ignite normally.

Checklist

1. Put away tools and instruments. Clean up debris.
2. Verify that blower OFF−DELAY time is selected as de-
sired.
3. Verify that blower and burner access doors are properly in-
stalled.
4. Cycle test furnace with room thermostat.
5. Check operation of accessories per manufacturer's instruc-
tions.
6. Review User's Guide with owner.
7. Attach literature packet to furnace.
34
EXAMPLE:
Specifications are subject to change without notice.
THERMOSTAT SUBBASE
TERMINALS WITH
THERMOSTAT REMOVED
(ANITICIPATOR, CLOCK, ETC.,
MUST BE OUT OF CIRCUIT.)
HOOK-AROUND
AMMETER
R Y W G
10 TURNS
FROM UNIT 24-V
CONTROL TERMINALS
= 0.5 AMPS FOR THERMOSTAT
5.0 AMPS ON AMMETER
ANTICIPATOR SETTING
10 TURNS AROUND JAWS
Fig. 42 − Amp. Draw Check with Ammeter
A96316
441 01 1422 00