GM9S80 Service Manual
SCHEDULED MAINTENANCE
26
The bearings in the induced draft blower and circulator blow-
er motors are permanently lubricated by the manufacturer.
No further lubrication is required. Check motor windings for
accumulation of dust which may cause overheating. Clean
as necessary.
Under some conditions, the fuel or air supply can create a
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Periodically during the heating season make a visual check of
a few minutes since any dislodged dust will alter the normal
blue with slightly orange tips. They should not be yellow. They
Proper test equipment for accurate diagnosis is as essential
as regular hand tools.
The following is a must for every service technician and ser-
vice shop.
1. Thermometers or thermocouple meter (optional) - To
measure temperatures.
2. Multi-Meter - To measure amperage and voltage, to
test continuity, capacitors, and motor windings.
3. Manometer - To measure static pressure, pressure
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let and manifold gas pressures.
Other recording type instruments can be essential in solving
abnormal problems, however, in many instances they may
be rented from local sources.
accurate repairs resulting in fewer call backs.
Before attempting to diagnose an operating fault code, run
a Heating Performance Test to determine if the heating sys-
tem is performing within 5% of the BTU input found on the
rating plate of the unit being tested. To conduct a heating
performance test, the BTU input to the unit must be calculat-
ed (see Clocking a Gas Meter). Before clocking a gas meter,
contact your local utility to provide the caloric value (BTU
content) of the natural gas in the area.
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umn). How-to instructions can be found in the service man-
Temperature Rise.