62
SERVICING
VOLT / OHM
METER
COLOR
IDENTIFYING
TAB
Testing Primary Limit Control
4. After completing check and/or replacement of primary
limit control, reinstall burner compartment door.
5. Turn on electrical power and verify proper unit operation.
S-301 CHECKING AUXILIARY LIMIT CONTROL
The auxiliary limit control is designed to prevent furnace op-
eration in case of main blower failure in horizontal installa-
tions. It may also open if the power supply is interrupted
while the furnace is firing.
The auxiliary limit control is suitable for both horizontal right
and horizontal left installations. Regardless of airflow direc-
tion, it does not need to be relocated. The (2) two auxiliary
limits are located on the blower housing (one on each side),
as shown in the following illustration.
AUXILIARY LIMIT
CONTROL
AUXILIARY LIMIT
CONTROL
BLOWER HOUSING
Auxiliary Limit Control Location
WARNING
HIGH
VOLTAGE
D
ISCONNECT
ALL
POWER BEFORE SERVICING OR
INSTALLING THIS UNIT.
M
ULTIPLE POWER SOURCES MAY
BE PRESENT.
F
AILURE TO DO SO MAY CAUSE PROPERTY
DAMAGE, PERSONAL INJURY OR DEATH.
1.
Remove blower compartment door to gain access to
the auxiliary.
2.
Remove the wires from the auxiliary limit control termi-
nals.
3.
Using an ohmmeter, test for continuity across the two
terminals.
VOLT / OHM
METER
RED
RESET
BUTTON
COLOR
IDENTIFYING
TAB
Testing Auxiliary Limit Control
