GC9C80 Service Manual
SERVICING
35
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.
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 orice(s) deformed, or out of alignment to
burner - replace.
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 ame.
T
T R TR RG T T T
T B RR R GR
T R
BR RRG R T B
The ground wire must run from the furnace all the way back
to the electrical panel. Proper grounding can be conrmed by
disconnecting the electrical power and measuring resistance
between the neutral (white) connection and the burner closest
to the ame sensor. Resistance should be less than 2 ohms.
The ignition control is a combination electronic and
electromechanical device and is not eld repairable. Complete
unit must be replaced.
TG RT
A ame sensing device is used in conjunction with the ignition
control module to prove combustion. If proof of ame is not
present the control will de-energize the gas valve and “retry”
for ignition or lockout.
G
TG
T
R BR RG R
TG T
T
T R
R
B RT
R T RRT
G R JR
R T
Flame current can be measured by putting a D.C. microamp
meter in series with the ame rod.
TG RT
3. As soon as ame is established a micro-amp reading
should be evident once proof of ame (micro-amp reading)
is established, the hot surface ignitor will be de-energized.
4. The Integrated Ignition controls will have 1 to 4 micro-
amps. If the micro-amp reading is less than the minimum
specied, check for high resistance wiring connections,
sensor to burner gap, dirty flame sensor, or poor
grounding.
5. If absolutely no reading, check for continuity on all
components and if good - replace ignition control module.
Contaminated fuel or combustion air can create a
nearly invisible coating on the ame sensor. This coating
works as an insulator causing a loss in the ame sense signal.
If this situation occurs the ame sensor must be cleaned with
steel wool.
G
TG
T
R BR RG R
TG T T
T R R
B RT
R T RRT
G R JR R T
T T TTR T R
T
G
T GTR B T BR GR RG G R
BRT RT R GTR R
RR R T GTR