Checking Hot Surface Igniter; Checking Pressure Transducer; Checking For Delayed Ignition; Checking Intergrated Ignition Control - Goodman GMES8 U Series Service And Troubleshooting

SERVICING

CHECKING HOT SURFACE IGNITER

120V Silicon Nitride Igniter - ULN furnaces use a 120V
silicone nitride igniter, part #0130F00717. The normal
operating temperature is approximately 2156°F - 2678°F. At
room temperature the igniter ohm reading should be from
20-100 ohms.
L
INE VOLTAGE NOW PRESENT
CHECKING PRESSURE TRANSDUCER (80% ULN)
The 80% ULN products utilize a pressure transducer (in lieu
of a pressure switch). The pressure transducer signals the
control board to modulate the heating cycle during a call
for heat by regulating the induced draft motor speed. By
regulating the speed of the induced draft motor, proper air-
fuel ratios are maintained.
Sensing range specification:0.0-4.0 inches W.C.
Voltage specifications:
• Steady State: 5.0 vDC from red to green wire (transducer
wiring harness input)
• With Inducer off: 0.5 vDC from black to green wire
(transducer wiring harness output).
• During operation: Output range equals 0.5 - 4.5 vDC
Potential errors:
1. Control board does not receive 0.25 vDC for inducer motor
with motor off
a.Will result in 2-flash error code on the control board
2. Control board does not receive the required voltage
change (0.5 - 4.5 vDC) during inducer motor operation.
a. Will result in 3-flash error code on the control board

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
CHECKING GAS PRESSURE).
22
WARNING
FIELD TEST MODE
Function: When the SW1 button is pressed and held until
the LED is blinking in AMBER (more than 10 seconds, less
than 15 seconds), the control will execute a field test mode
sequence to cycle through component operation.
Operation: The control must be powered and the thermostat
satisfied (no call for heat or cool). Depress and hold the SW1
button for at least 10 seconds (but not more than 15 seconds),
until the LED is blinking in AMBER, then release. The control
will execute the following functions:
1. Blower - "Heat" Speed 15 seconds
2. Blower - "Cool" Speed 15 seconds
3. Blower - "Fan" Speed 15 seconds
4. Hot Surface Igniter 17 seconds
5. Inducer - "Run" setting 15 seconds
6. Inducer - 2.0" w.c. 60 seconds
7. Return to OFF mode
Once the Field Test Mode is initiated, all thermostat inputs
will be ignored until the field test sequence is completed. If
the SW1 button is held for more than 15 seconds, the button
press will be ignored and the LED display will return to its
prior state.
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 10 ohms.
The ignition control is a combination electronic and
electromechanical device and is not field repairable. Complete
unit must be replaced.
L
INE VOLTAGE NOW PRESENT
These tests must be completed within a given time frame due
to the operation of the ignition control.
NOTE: The models use PCBF161 with ID Plug.
WARNING
D
ISCONNECT POWER
WARNING