Carrier N80ESL Series Installation Instructions Manual Download Page 33

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Specifications are subject to change without notice.

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6. Set thermostat heat anticipator.

a. Mechanical thermostat -- Set thermostat heat anticipator

to match the amp. draw of the electrical components in
the R--W circuit. Accurate amp. draw readings can be ob-
tained at the wires normally connected to thermostat sub-

base terminals, R and W. The thermostat anticipator
should NOT be in the circuit while measuring current.

(1.) Remove thermostat from subbase or from wall.
(2.) Connect an amp. meter as shown in Fig. 43 across

the R and W subbase terminals or R and W wires at

wall.

(3.) Record amp. draw across terminals when furnace is

in heating and after blower starts.

(4.) Set heat anticipator on thermostat per thermostat in-

structions and install on subbase or wall.

b. Electronic thermostat: Set cycle rate for 4 cycles per hr.

7. Adjust blower off delay The blower off delay has 4 ad-

justable settings from 90 sec to 180 sec. The blower off
delay jumpers are located on the furnace control board.

(See Fig. 24.)
To change the blower off delay setting, move the jumper
from one set of pins on the control to the pins used for the

selected blower off delay. Factory off delay setting is 120
sec.

8. Set airflow CFM for cooling

Select the desired blower motor speed lead for cooling air-
flow. See Table 5--Air Delivery--CFM (With Filter) for

lead color identification.

Check Safety Controls

The flame sensor, gas valve, and pressure switch were all checked

in the Start--up procedure section as part of normal operation.

1. Check Main Limit Switch(es)

This control shuts off combustion control system and en-

ergizes air--circulating blower motor, if furnace overheats.
By using this method to check limit control, it can be es-
tablished that limit is functioning properly and will operate

if there is a restricted duct system or motor failure. If limit
control does not function during this test, cause must be

determined and corrected.

a. Run furnace for at least 5 minutes.

b. Gradually block off return air with a piece of cardboard

or sheet metal until the limit trips.

c. Unblock return air to permit normal circulation.

d. Burners will re--light when furnace cools down.

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.