GM9S96 Service Manual
SERVICING
36
The following drawing illustrates the style of limit switches
used on the 90% furnaces.
ENCLOSED DISK
FRONT VIEW SIDE VIEW
WARNING
-
1. Remove burner compartment door to gain access to
the primary limit.
2. Remove low voltage wires at limit control terminals.
3. With an ohmmeter, test between these two terminals
as shown in the following drawing. The ohmmeter
should read continuous unless heat exchanger tem-
perature is above limit control setting. If not as above,
replace the control.
RED
RESET
BUTTON
COLOR
IDENTIFYING
COLOR
IDENTIFYING
TAB
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.
To aid in identifying these controls, refer to the Primary Limit
Charts in furnace Technical Manual for part number, tem-
perature setting and color(s) code.
The
limit switch for control of high temperatures within the fur-
nace or duct work. This control is preset, nonadjustable and
auto reset. The control is located in the blower compartment
of the furnace on the blower deck, as shown in the following
illustration.
WARNING
-
WARNING
-
To aid in identifying these controls, color coded labels are
attached to the back of the controls. Refer to the Auxiliary
Limit Charts in furnace Technical Manual for color codes and
temperature settings.