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
        
          

 





-
-



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
-
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.


-
umn). How-to instructions can be found in the service man-

Temperature Rise.