Amana GUIA Series Service Instructions Manual page 129

SERVICING
S-6 CHECKING AUXILIARY LIMIT CONTROL
All the 80% and 90% furnaces use an additional limit switch
required for safety control of high temperature within the fur-
nace or duct work. This control is preset, nonadjustable and
must be manually reset. The control is located in the blower
compartment of the furnace either on the blower deck or
blower housing.
The auxiliary manual reset limit is located on the lower side
of the blower deck, near the center, on all 80% furnaces and
on the 90% GUCA and GUSA furnaces, as shown in the
following illustration.
AUXILIARY LIMIT
CONTROL
Auxiliary Limit Control Location
(All 80% Furnaces & 90% GUCA Furnace)
The auxiliary manual reset limits (Qty 2) are located on the
blower housing (one on each side) on 90% GCCA and GUVA
furnaces, as shown in the following illustration.
AUXILIARY LIMIT
CONTROL
BLOWER HOUSING
Auxiliary Limit Control Location
(90% GCCA & GUVA Furnaces)
The auxiliary limit control is connected in series with the
primary limit control wiring to the integrated ignition control.
If its temperature should be exceeded, it will open, interrupt-
ing the voltage to the gas valve causing it to close.
BLOWER DECK
AUXILIARY LIMIT
CONTROL
If this limit control opens, the air circulation blower and in-
duced draft blower will run continuously on models with White-
Rodgers 50A50, 50A51 or Heatcraft HSI 1-1A ignition con-
trol. On models with the White-Rodgers 50A55, 50M61,
50V61 or Heatcraft HSI-2 ignition control, "only" the air
circualtion blower will run continuously. The diagnostic light
will flash four times. These symptoms are identical to a trip
of the primary limit control.
The auxiliary limit control is designed to prevent furnace
operation in case of main blower failure on horizontal or
counterflow installations. It may also open if the power sup-
ply 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.
WARNING
Disconnect Electrical Power Supply
1. Remove blower compartment door to gain access to the
auxiliary limit control which is located on the lower side
of the blower deck on all 80% furnaces and on 90% GUCA
and GUSA furnaces, or on the blower housing on 90%
GCCA and GUVA furnaces.
2. Remove the wires from the auxiliary limit control termi-
nals.
3. Use an ohmmeter, test for continuity across the two ter-
minals (refer to the following auxiliary limit control fig-
ure). No reading indicates the control is open. Push red
reset button, test again - if still open, replace the con-
trol.
VOLT / OHM
METER
Testing Auxiliary Limit Control
(80% & 90% Furnaces)
RED
RESET
BUTTON
COLOR
IDENTIFYING
TAB
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