Checking Primary Limit Control; Checking Auxiliary Limit Control - Goodman AMH8 Service Instructions Manual

SERVICING
S-300 CHECKING PRIMARY LIMIT CONTROL
All use a nonadjustable, automatic reset, bi-metal type limit
control. Refer to the following drawing for the location of
the primary limit.
Primary Limit Control Location
(80% Upflow Furnace Shown, Counterflow Similar)
Style 1 drawing illustrates the Primary Limit used on the
80% furnaces.
HIGH VOLTAGE
D ALL
ISCONNECT POWER BEFORE SERVICING OR
CHANGING ANY ELECTRICAL WIRING.
F
SOURCES MAY BE PRESENT. AILURE TO DO SO MAY CAUSE
PROPERTY DAMAGE, PERSONAL INJURY OR DEATH.
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.
Location of Primary Limit
Style 1
WARNING
M
ULTIPLE POWER
Testing Primary Limit Control
S-301 CHECKING AUXILIARY LIMIT CONTROL
Automatic Reset Auxiliary Limit Located in Blower
Scroll
The 80% "H" model furnaces use an auxiliary limit (au-
tomatic reset) control connected in series with the gas
valve and integrated control module. If its temperature
should be exceeded, it will open, interrupting the voltage to
the gas valve causing it to close. The auxiliary limit is lo-
cated on the front side of the blower housing, near the
center, on all 80% single-stage furnaces, as shown in the
following illustration.
BLOWER HOUSING
AUXILIARY LIMIT CONTROL
Auxiliary Limit Control Location
53