High Altitude Application; Checking For Delayed Ignition; Checking Integrated; Ignition Control Boards - Goodman GMVM Service Instructions Manual

SERVICING
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 figures.
MODULATING FURNACE PNEUMATIC TUBING DIAGRAM
Low & High Pressure Switch Assembly
Front Cover
Pressure Switch
Black Tee
MUST
be left open
Upflow Model Shown
For representation only. Actual unit may vary in appearance.
S-311 HIGH ALTITUDE APPLICATION
Modulating furnaces are approved up to 10,000 ft alti-
tude. No kit or changes are needed.
S-312 CHECKING FOR DELAYED IGNITION
Delayed ignition is a delay in lighting a combustible mix-
ture of gas and air which has accumulated in the combus-
tion chamber.
When the mixture does ignite, it may explode and/or rollout
causing burning in the burner venturi.
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 lo-
cating 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.
with "H" Fitting
Modulating
Gas Valve
+ Port is Open
Negative (-)
to the Atmosphere
Port on Gas Valve
S-313 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.
WARNING
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 resis-
tance 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 electro-
mechanical device and is not field repairable. Complete unit
must be replaced.
WARNING
L
INE VOLTAGE NOW PRESENT
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 PCBKF200 and
PCBKF201 controls utilize a dual, 7-segment LED display
to indicate diagnostic codes.
When the control is powered up normally the light will be on
continuously. The PCBKF200 and PCBKF201displays will
indicate "ON" when powered and in standby mode.
This can be used to test for 120 volts and 24 volts to the
control since both must be present for the light to be on. If
this step fails, check for 120 volts to the control and check
the transformer and its associated wiring. If this step is suc-
cessful give the control a call for heat and wait five (5) sec-
onds or until the furnace goes into lockout. If the control
detects a failure it will now be shown on the diagnostic indi-
cator light/display. Refer to the Abnormal Operation section
in the Sequence of Operation section of this manual for more
detail on failure codes
The indicator light/display may be viewed by looking through
the sight glass in the blower compartment door. The failure
codes are retrieved via an on-board, momentary push button
switch. Pressing the button for 2-5 seconds will force the
failure codes to be displayed on the diagnostic indicator.
D
ISCONNECT POWER
73