Manual Fan On; Combustion Quality; Venting; Condensate Drainage - Goodman GMEC96 Series Service And Troubleshooting

SYSTEM OPERATION
• The circulator fan is energized at cool speed after a
cool on delay. The electronic air cleaner will also be
energized.
• After the thermostat is satisfied, the compressor is
de-energized and the Cool Mode FanOff Delay period
begins.
• Following the 60 second Cool Mode Fan Off Delay
period, the cool circulator and air cleaner relay are de-
energized

MANUAL FAN ON:

• On a call for Fan, the G thermostat contacts close
signaling the control module.
• The LED will display a solid "GREEN"
• When a call for G is received, the control will energize
the circulator in low heat speed after the fan on delay
time expires. The electronic air cleaner will also be
energized at this time.
• When the thermostat fan switch is moved to the ON
position, the circulator blower is energized at low heat
speed and the electronic air cleaner is also energized
• When the thermostat fan switch is moved back to the
AUTO position, the circulator fan and air cleaner relay
are de-energized and the control awaits a thermostat
call for heat or cool.
• Exception: During the Cool "On"delay, the control will
not respond to the fan input. If the fan was called prior
to the call for cool, the circulator will remain energized
during the Cool "On"delay.
• If the fan is called prior to a call for heat, the circulator
will remain energized during the entire call for heat
sequence.

Combustion Quality

Combustion quality can be affected by several factors. Major
factors are venting and draining.

Venting

The venting system should be planned and installed with the
following in mind;
• Should not be longer than necessary
• Use 45°elbows rather than 90° elbows when possible
• Must not sag or otherwise trap condensate
• Use longest radius fittings possible
• If using 3" venting, make the transition from 2" to 3" as
close as practically possible
• Make sure there is no flue gas recirculation into the
combustion air pipe

Condensate Drainage

Furnace combustion can be affected if a furnace is holding
condensate. Check for proper connections of drain hoses,
make sure furnace condensate trap is clean. Make sure
furnace is not improperly sloped. Make sure air conditioning
coil drain is not interfering with furnace drain.
Other Causes
1. Manifold Gas Pressure must be set for the gas being used,
Natural or L.P., high and low firing rates. If converted to
L.P. gas, check size of all orifices
2. Remove Draft Inducer, Check the integrity of the gasket
between the inducer and the collector box cover, any
air leak here will have a negative effect on combustion.
Check the orifice hole in the collector box, it must be free
of burrs on both sides
3. Make sure burners are clean, not out of position and line
up correctly with exchanger tubes, including the heat
exchanger orifice plate between the burners and the
heat exchanger tubes, make sure it is not loose, missing
a screw or hanging down between the burners and heat
exchangers causing flame impingement.
4. Make sure the field installed gas line is not binding and
causing distortion of burner assembly
5. If the furnace is installed as a one pipe system; make
sure the surrounding area and structure are adequate to
provide combustion air
6. Make sure there are no cabinet air leaks allowing supply
air to affect combustion
7. If heat exchanger integrity is uncertain, follow procedures
in Service Bulletin SF-041
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