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Primary Limit Control
The primary limit control is located on the partition panel and
monitors heat exchanger compartment temperatures. It is a
normally closed (electrically), automatic reset, temperature-
activated sensor. The limit guards against overheating as a result
of insufficient conditioned air passing over the heat exchanger.
Auxiliary Limit Controls
The auxiliary limit controls are located on or near the circulator
blower and monitors blower compartment temperatures. They
are normally-closed (electrically), auto-reset sensors. These limits
guard against overheating as a result of insufficient conditioned
air passing over the heat exchanger.
Rollout Limit Controls
The rollout limit controls are mounted on the burner/manifold
assembly and monitor the burner flame. They are normally-
closed (electrically), manual-reset sensors. These limits guard
against burner flames not being properly drawn into the heat
exchanger.
Pressure Switches
The pressure switches are normally-open (closed during
operation), negative air pressure-activated switches. They
monitor the airflow (combustion air and flue products) through
the heat exchanger via pressure taps located on the induced
draft blower and the coil front cover. These switches guard
against insufficient airflow (combustion air and flue products)
through the heat exchanger and/or blocked condensate drain
conditions.
Flame Sensor
The flame sensor is a probe mounted on the burner/manifold
assembly which uses the principle of flame rectification to
determine the presence or absence of flame.
MAINTENANCE
WARNING
HIGH VOLTAGE!
Goodman 74
To avoid personal injury or death due to
electrical shock, disconnect electrical power
before performing any maintenance. If you
must handle the igniter, handle with care.
Touching the igniter element with bare fingers,
rough handling or vibration could damage the igniter
resulting in premature failure. Only a qualified servicer
should ever handle the igniter.
Annual Inspection
The furnace should be inspected by a qualified installer, or
service agency at least once per year. This check should be
performed at the beginning of the heating season. This will
ensure that all furnace components are in proper working order
and that the heating system functions appropriately. Pay
particular attention to the following items. Repair or service as
necessary.
Flue pipe system. Check for blockage and/or leakage. Check
the outside termination and the connections at and internal to
the furnace.
Heat exchanger. Check for corrosion and/or buildup within
the heat exchanger passageways.
Burners. Check for proper ignition, burner flame and flame
sense.
Drainage system. Check for blockage and/or leakage. Check
hose connections at and internal to furnace.
Wiring. Check electrical connections for tightness and/or
corrosion. Check wires for damage.
Filters
CAUTION
Goodman 119
To ensure proper unit performance, adhere to the filter
sizes given in the Recommended Minimum Filter Size
chart or Specification Sheet applicable to your model.
NOTE: Please contact your distributor or our website for the
applicable Specification Sheet referred to in this manual.
Filter Maintenance
Improper filter maintenance is the most common cause of
inadequate heating or cooling performance. Filters should be
cleaned (permanent) or replaced (disposable) every 2 months or
as required. When replacing a filter, it must be replaced with a
filter of the same type and size.
Filter Removal
Depending on the installation, differing filter arrangements can be
applied. Filters can be installed in either the central return register
or a side panel external filter rack (upflow only).
A media air filter or electronic air cleaner can be used as an
alternate filter. Follow the filter sizes given in the Recommended
Minimum Filter Size chart to ensure proper unit performance.
To remove filters from an external filter rack in an upright upflow
installation, follow the directions provided with external filter rack
kit.
Horizontal Unit Filter Removal
Filters in horizontal installations are located in the central return
register or the ductwork near the furnace.
To remove:
1. Turn off electrical power to the furnace.
2. Remove the filter(s) from the central return register or
ductwork.
3. Replace the filter(s) by reversing the procedure for removal.
4. Turn on electrical power to the furnace.
Media Air Filter or Electronic Air Cleaner Removal
Follow the manufacturer's directions for service.
Filters
29
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