Checking For Delayed Ignition; Checking Integrated Ignition Control Boards; High Altitude Application (Usa) - Goodman GMEC96 Series Service And Troubleshooting

SERVICING
pressure switch keeps the gas valve from opening in the event
of condensate backing up in the secondary heat exchanger.
This could occur from improperly connected drains or a
plugged drain tube.
1. Remove burner compartment door to gain access to
pressure switch(es).
2. Remove wires from the pressure switch(es) electrical
terminals.
3. Remove the pressure control hose from the control and
interconnect with an inclined manometer as shown in the
following figures.
4. With an ohm meter connected across the pressure switch
terminals; with the inducer running the switch should close
and the ohm meter should show a complete circuit across
the pressure switch. If the switch is not closed, compare
the negative pressure to the
the particular switch. Either the switch is defective or the
inducer / venting system is inadequate.
* * *
M 1
P 3
O F *
F
C 2
O N
*
* *
COIL COVER
PRESSURE SWITCH
INDUCED
DRAFT
BLOWER
Blower Pressure Switch
Negative Pressure Measurement

HIGH ALTITUDE APPLICATION (USA)

The furnace as shipped requires no change to run between
0 - 7500 feet. Do not attempt to increase the firing rate
by changing orifices or increasing the manifold pressure
below 7500 feet. feet. This can causepoor combustion and
equipment failure. High altitude installations above 7500
feet. feet may require both a pressure switch and an orifice
change. These changes are necessary to compensate for
the natural reduction in the density of both the gasfuel and
the combustion air at higher altitude.
For installations above 7500 feet. feet, please refer to your
distributor for required kit(s). Contact the distributor for a
tabular listing of appropriate manufacturer's kits for propane
gas and/or high altitude installations. The indicated kits must
be used to insure safe and proper furnace operation. All
conversions must be performed by a qualified installer, or
56
closing point specified for
INDUCED DRAFT BLOWER
PRESSURE SWITCH
PRESSURE SWITCH
HOSE
OPEN TO
ATMOSPHERE
1/4" TEE
-.
HOSE TO INDUCED
DRAFT BLOWER TAP
service agency.
In some areas the gas supplier may artificially derate the
gas in an effort to compensate for the effects of altitude. If
the gas is artificially derated the appropriate orfice size must
be determined based on the BTU/ft
gas and the altitude. Refer to the National Fuel Gas Code,
NFPA 54/ANSI Z223.1, and information provided by the gas
supplier to determine the proper orifice size.

CHECKING FOR DELAYED IGNITION

Delayed ignition is a delay in lighting a combustible mixture
of gas and air which has accumulated in the combustion
chamber.
Furnace design makes this extremely unlikely unless safety
controls have been by-passed or tampered with. Never by-
pass or alter furnace controls.
If delayed ignition should occur, the following should be
checked:
1. Improper gas pressure - adjust to proper pressure (See
S-307 CHECKING GAS PRESSURE).
2. Improper burner positioning - burners should be in locating
slots, level front to rear and left to right.
3. Carry over (lighter tube or cross lighter) obstructed - clean.
4. Main burner orifice(s) deformed, or out of alignment to
burner - replace.
CHECKING INTEGRATED IGNITION
CONTROL BOARDS
NOTE: Failure to earth ground the furnace, reversing the
neutral and hot wire connection to the line (polarity), or a
high resistance connection in the neutral line may cause the
control to lockout due to failure to sense flame.
T
O AVOID THE RISK OF ELECTRICAL SHOCK, WIRING TO THE UNIT
MUST BE PROPERLY POLARIZED AND GROUNDED.
BEFORE PERFORMING SERVICE LISTED BELOW.
The ground wire must run from the furnace all the way back
to the electrical panel. Proper grounding can be confirmed by
disconnecting the electrical power and measuring resistance
between the neutral (white) connection and the burner closest
to the flame sensor. Resistance should be less than 2 ohms.
The ignition control is a combination electronic and
electromechanical device and is not field repairable. Complete
unit must be replaced.
These tests must be completed within a given time frame due
to the operation of the ignition control.
The ignition control is capable of diagnosing many furnace
failures to help in troubleshooting. The trial for ignition period
content of the derated
3
WARNING
D
ISCONNECT POWER