Southbend CG90-1 - Manual (Page 28)

T ROUBLESHOOTING C OMBINATION O VEN
P AGE 28 O PERATOR ’ S M ANUAL 1180963
TROU
BLE
S
H
OOTI
N
G
Gas Error
Gas Error
Ensure that gas shut-off valve is open.
Check gas supply pressure. (There is an inlet pressure tap on the gas combination valve that can be
used for this purpose.) Supply pressure should be > 7" W.C. for natural gas or > 11" W.C. for propane.
Remove front lower panel and burner box cover. Turn unit on. Observe ignitors for first 101 seconds after
turning unit on. Ignitors should begin glowing and continue to glow for approximately 37 seconds.
(If the flame does not light on first attempt, this process will be repeated two additional times.)
Do
both ignitors
glow?
Does
one ignitor
glow?
Do both pilot
flames light (at least
temporarily)?
Place test leads
between terminal
TB-C2 and TB-C1.
Turn unit on. Check
voltage during first
30 seconds of
operation.
Test and replace
bad ignitor, as
required.
Check manifold pressure during first 30
seconds of operation. (There is a tap on
gas combination valve for this purpose.)
Make sure that flame
sensors are
positioned at tip of
inner core of pilot
flame and are not
touching any metal
surface. Retry.
Is voltage
approximately 24
volts?
Replace RAM
module.
Replace both
ignitors.
Is manifold pressure approximately
4" W.C. for natural gas or approximately
10" W.C. for propane?
Replace gas valve.
Remove burner box. Remove pilot supply tube from pilot(s) not lighting.
Examine and replace pilot orifice if necessary. Replace pilot if damaged.
Ensure that ignitor is positioned properly relative to pilot. Adjust as necessary.
No Yes
Yes No
No Yes
No
No Yes
Done
Yes No
Check and replace RAM
module and flame sensor,
as necessary.
Does main
burner come
on (with door
closed)?
Is voltage
approximately 24
volts?
Check and replace
RAM module, as
necessary.
Yes No
Check voltage
between P and C
terminals on gas
valve during first 30
seconds of operation.
Yes