Induced Draft Blower Motor; Checking Gas Valve (Redundant); Checking Main Burners; Checking Orifices - Goodman Amana ComfortNet GMVC8 Service Instructions Manual

SERVICING
S-303 INDUCED DRAFT BLOWER Motor
HIGH VOLTAGE
D ALL
ISCONNECT POWER BEFORE SERVICING OR
M
INSTALLING THIS UNIT. ULTIPLE POWER SOURCES MAY
F
BE PRESENT. AILURE TO DO SO MAY CAUSE PROPERTY
DAMAGE, PERSONAL INJURY OR DEATH.
1. Remove burner compartment door to gain access to
the induced draft blower motor.
2. Disconnect the motor wire leads from its connection
point at the induced draft motor.
3. Using a ohmmeter, test for continuity between each
of the motor leads.
4. Touch one probe of the ohmmeter to the motor frame
(ground) and the other probe in turn to each lead.
If the windings do not test continuous or a reading is
obtained to ground, replace the motor.
5. If the windings have a continuity reading, reconnect
wires. Turn power on to the furnace and turn the
thermostat on in the heating mode. Check voltage
for 115V at the induced draft motor terminals during
the trial for ignition. If you have 115V and the motor
does not run, replace the induced draft motor.
6. After completing check and/or replacement of in-
duced draft motor, reinstall burner compartment door.
7. Turn on electrical power and verify proper unit opera-
tion.
S-304 CHECKING GAS VALVE (Redundant)
A combination redundant operator type gas valve which pro-
vides all manual and automatic control functions required
for gas fired heating equipment is used.
The valve provides control of main burner gas flow, pres-
sure regulation, and 100 percent safety shut-off. Gas valves
must be checked by confirming that 24 vac is present be-
tween C and Low (main) while proper gas pressure is sup-
plied to the valve.
WARNING
D ALL
ISCONNECT POWER BEFORE SERVICING
S-305

CHECKING MAIN BURNERS

The main burners are used to provide complete combus-
tion of various fuels in a limited space, and transfer this
heat of the burning process to the heat exchanger.
Proper ignition, combustion, and extinction are primarily
due to burner design, orifice sizing, gas pressure, primary
and secondary air, vent and proper seating of burners.
80
WARNING
.023" - .027"
Beckett Burner
WARNING
D ALL G
ISCONNECT AS AND
In checking main burners, look for signs of rust, oversized
and undersized carry over ports restricted with foreign ma-
terial, etc, refer to previous drawing. Burner slots must not
be altered in size.
S-306

CHECKING ORIFICES

A predetermined fixed gas orifice is used in all of these fur-
naces. That is an orifice which has a fixed bore and position
as shown in the following drawing.
No resizing should be attempted until all factors are taken
into consideration such as inlet and manifold gas pressure,
alignment, and positioning, specific gravity and BTU con-
tent of the gas being consumed.
The only time resizing is required is when a reduction in
firing rate is required for an increase in altitude.
Orifices should be treated with care in order to prevent dam-
age. They should be removed and installed with a box-end
wrench in order to prevent distortion. In no instance should
an orifice be peened over and redrilled. This will change the
angle or deflection of the vacuum effect or entraining of pri-
mary air, which will make it difficult to adjust the flame prop-
erly. This same problem can occur if an orifice spud of a
different length is substituted.
WARNING
D ALL G
ISCONNECT AS AND
1. Check orifice visually for distortion and/or burrs.
2. Check orifice size with orifice sizing drills.
3. If resizing is required, a new orifice of the same physical
size and angle with proper drill size opening should be
E P S
LECTRICAL OWER UPPLY.
E P S
LECTRICAL OWER UPPLY.