TROUBLESHOOTING
8-9
6.
If there is an increase in gas pressure,
replace the gas train.
8.5 LOCK OUT RUN AIR PRESSURE
A LOCKOUT RUN AIR FLOW indicates that the
air pressure, while firing, was too low for
operation. Oscillations or rumbling of the unit is
also a common cause this fault.
8.6.1 Determining the Cause of the Fault
8.6.2 Oscillations
8.6.3 Blower
8.6.4 Blower Proof Switch
8.6.5 Motor Contactor
Recommended Troubleshooting Equipment
AC Voltmeter
Ohmmeter
8.6.1 DETERMINING THE CAUSE OF THE
FAULT
1. Clear the Annunciator and start the unit.
2. If the unit does not fault after proving flame,
proceed to Section 8.5.2.
3. If the blower does not start
,
proceed to
Section 8.5.3.
4. If the blower starts but the Annunciator
displays LOW AIR FLOW, proceed to
Section 8.5.4.
5. If the unit has sealed combustion air ducted
in right up to the blower, check the ducting
for blockage.
6. If combustion air is ducted into the room, or
brought in through a louver, be sure that the
size of the ducting or louver is adequate.
Ensure that the louvers are open while the
unit is firing.
8.6.2 OSCILLATIONS
Oscillations, also known as rumbling, typically
occur when the air/fuel mixture is too lean. This
causes the flame to burn at various distances
from the burner at a rapid pace. Oscillations
create pressure waves that can trip the air
pressure switch, shutting the unit
off.
1. Start the unit.
2. Slowly increase the firing rate percentage
while listening to the unit.
3. If a rumbling sound is heard, at higher firing
rates, 60% to 100%, combustion calibrate
the unit as per sections 4.3 and 4.4.
8.6.3 BLOWER
1. Locate wire #81 & #83 on the motor
contactor located inside the control panel.
2. Connect an AC voltmeter between wire #81
and wire #83 and the unit frame.
3. Start the unit.
4. The AC voltmeter should measure between
200 and 230VAC.
5. If 200 to 230VAC is not measured, proceed
to section 8.5.5
6. If 200 to 230VAC is measured, check for
voltage between wire #131 and #132 at the
blower motor.
7. If 200 to 230 VAC is present between wire
#131 and #132 and the blower still does not
start replace the blower assembly.
8.6.4 BLOWER PROOF SWITCH
1. Remove wires #154 and #155 from the
blower proof switch
2. Connect an ohmmeter across the blower
proof switch and start the unit.
3. The blower proof switch should show
continuity with the blower running.
4. If the blower proof switch does not show
continuity, remove the switch and check for
signs of blockage. Remove any debris and
reinstall the switch. Retest as per Steps 2
through 3 in this section.
5. If the blower proof switch shows continuity,
disconnect AC power to the unit.
6. Disconnect the 1 ¾" connector from the
control panel.
7. Referring to system schematic 161453 in
Appendix H, locate wire #154 and #155 and
check both for continuity.
8. Check the switch end of wires #154 and
#155 for loose connections.
9. Check the pins on the 1 ¾" connector for
proper pin insertion or wear.
10. If continuity, the connector and pins are
okay, reconnect wires #154 and #155 to the
blower proof switch.
Summary of Contents for Benchmark G-00-711
Page 62: ...APPENDIX C ix Temperature Sensor Resistance Chart Balco ...
Page 69: ...APPENDIX F xvi ...
Page 70: ...APPENDIX F xvii ...
Page 71: ...APPENDIX F xviii ...
Page 72: ...APPENDIX F xix ...
Page 73: ...APPENDIX F xx ...
Page 74: ...APPENDIX G xviii ...
Page 75: ...APPENDIX G xix ...
Page 76: ...APPENDIX H xxi ...
