79
Rev. 2
SERVICING
WARNING
Disconnect Electrical Power Supply:
1. Remove burner compartment door to gain access to pres-
sure switch.
2. Remove wires from the pressure switch electrical termi-
nals.
3. Using a VOM check from common terminal to NC (Nor-
mally Closed) - should read closed. Check from Com-
mon to NO (Normally Open) - should read open.
If switch reads as above proceed to Step 4, otherwise re-
place control.
4. Remove the pressure control hose from the control and
interconnect with an inclined manometer as shown in
the following figure.
Induced Draft Blower
Pressure Switch
Pressure Switch
Hose
1/4" Tee
Hose to Induced
Draft Blower Tap
Inclined Manometer
Open to
Atmosphere
Induced
Draft
Blower
ID Blower Pressure Switch
Negative Pressure Measurement
Reconnect pressure switch electrical wires.
WARNING
!
LINE VOLTAGE NOW PRESENT.
4. Energize furnace for heating cycle. The induced draft
blower motor will begin to run. The inclined manometer
should read approximately the negative pressure shown
in the pressure switch usage charts on pages 77 and
78.
Note: GUIA/B and GCIA/B furnaces can pull negative pres-
sures in excess of -3.0" WC. Use appropriate manometer
for measuring negative pressure. Refer to the charts on pages
77 and 78 for pressure switch usage and trip points.
5. Remove and check the two electrical wires and using
the VOM check from Common to NC (Normally Closed)
- should read open. Check from Common to NO (Nor-
mally Open) - should read closed. If not as above, re-
place control.
6. Reconnect wires to the control and place in a heating
cycle.
7. Begin to restrict the flue outlet until the pressure control
trips - cycling OFF the burner. The trip points should be
as shown on the preceeding pages.
8. If not as listed, replace control.
9. After completing check and/or repair of pressure switch,
reinstall burner compartment door.
10. Turn on electrical power and verify proper unit operation.
The pressure readings listed in the
PRESSURE SWITCH
USAGE AND TRIP POINT CHARTS on pages 77 and 78
must be adhered to for proper operation.
S-8A HIGH ALTITUDE PRESSURE SWITCH
For those altitudes starting at 7500 feet and above, it will be
necessary to replace the pressure switch and orifices.
These changes are required to compensate for the reduc-
tion in atmospheric pressure (less available air for combus-
tion) as the altitude increases.
High altitude pressure switches and kits are listed in the
Pressure Switch Usage and Trip Point Chart. Refer to sec-
tion
S-20 HIGH ALTITUDE APPLICATION (USA) for high
altitude orifice requirements.
S-9 CHECKING AIR CIRCULATOR BLOWER MO-
TOR OR INDUCED DRAFT BLOWER MOTOR
WARNING
Disconnect Electrical Power Supply
1. Remove blower compartment door to gain access to the
circulator blower motor and induced draft blower motor
wire leads connected at integrated ignition control.
2. Disconnect the motor wire leads from its connection point
at integrated ignition control module and capacitor if ap-
plicable.
3. Using and 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 ob-
tained to ground, replace the motor.
5. After completing check and/or replacement of circulator
blower motor or induced draft blower motor, reinstall
blower compartment door.
6. Turn on electrical power and verify proper unit operation.
Содержание GCIA045A30
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