Goodman ACVC96 BA Series, Service And Troubleshooting

Page: 53 / 65

SERVICING
53
Gas Rate Range Nominal
High Stage 9.7 to 10.3" w.c. 10.0" w.c.
Low Stage 5.7 to 6.3" w.c. 6.0" w.c.
Manifold Gas Pressure
Propane Gas
CHECKING HOT SURFACE IGNITOR
120V Silicon Nitride Ignitor - Amana® Brand and
Goodman® Brand A/GMVC96 and A/GCVC96 furnaces use
a 120V silicon nitride ignitor for ignition. The normal operating
temperature is approximately 2156°F - 2678°F.
D
IS C ONN EC T
ALL
POW ER B E FO RE S ER VI C ING .
WARNING
1. Remove burner compartment door to gain access to the
ignitor.
2. Ignitor cool - approximately 70 - 77°F.
3. Disconnect the ignitor from the Ignition Control.
4. Using an ohmmeter measure the resistance of the ignitor:
120 Volt Silicon Nitride : 120V Nitride Igniter should read
between 37 to 68 ohms.
5. Reconnect ignitor.
L
IN E VOLTAG E NOW P RE S E NT
WARNING
6. Place unit in heating cycle, measure current draw of ignitor
during preheat cycle.
The steady state current at 120V is 0.37 to 0.68 amps.
7. After checking and/or replacing of hot surface ignitor,
reinstall burner compartment door and verify proper unit
operation.
CHECKING FOR FLASHBACK
Flashback will also cause burning in the burner venturi, but is
caused by the burning speed being greater than the gas-air
flow velocity coming from a burner port.
Flashback may occur at the moment of ignition, after a burner
heats up or when the burner turns off. The latter is known as
extinction pop.
Since the end results of flashback and delayed ignition can
be the same (burning in the burner venturi) a definite attempt
should be made to determine which has occurred.
If flashback should occur, check for the following:
1. Improper gas pressure - adjust to proper pressure (See
S-307 CHECKING GAS PRESSURE
)..
2. Check burner for proper alignment and/or replace burner.
3. Improper orifice size - check orifice for obstruction.
CHECKING PRESSURE CONTROL
The pressure control is a safety device to prevent the
combustion cycle from occurring with inadequate venting
caused by a restricted or blocked vent pipe. In addition to the
high fire and low fire pressure switches, A/GMVC96 and A/
GCVC model furnaces have a “front cover pressure switch”
wired in series with the gas valve. This 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.
WARNING
HIGH VOLTAG E
D
IS C ONN EC T
ALL
POW ER B E FO RE S ER VI C ING O R
INSTALLING THIS UNIT .
M
ULTIPL E POW ER SOU RCE S MAY
B E P RE S E NT .
F
AILU RE TO DO SO MAY C AUS E P R OP ER TY
DAMAG E , P ER SONAL IN J U R Y O R D E ATH .
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
followi ng figure.
4. With an ohm meter connected across the pressure switch
terminals and 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 closing point
specified for the particular switch. Either the switch is
defective or the inducer/venting system is inadequate.
-.

OPEN TO
ATMOSPHERE
HOSE TO INDUCED
DRAFT BLOWER TAP
1/4" TEE
INDUCED DRAFT BLOWER
PRESSURE SWITCH
PRESSURE SWITCH
HOSE
INDUCED
DRAFT
BLOWER
*
*
*
* *
*
*
M 1
2
3 P
C
ON
O F F
COIL COVER
PRESSURE SWITCH
Blower Pressure Switch
Negative Pressure Measurement
(90% Upflow Furnace Shown, Counterflow Similar)
HIGH ALTITUDE APPLICATION (USA)
When furnaces are installed at high altitude, the appropriate
High Altitude Orifice or Pressure Switch Kit must be applied.
This is required due to the natural reduction in the density of
both the gas fuel and combustion air as altitude increases.
The High Altitude Orifice Kit will provide the proper design
certified input rate within the specified altitude range.
High Altitude Orifice or Pressure Switch Kits are purchased
according to the installation altitude and usage of either natural
or propane gas. Refer to the Technical Manual or product
Specification Sheet for a tabular listing of appropriate altitude
ranges and corresponding manufacturer’s high altitude (Natural
or Propane Gas) orifice or pressure switch kits.