AG2
Series
50
.
Does the heater have a relay board?
(identified with orange crescent
next to the terminal plug).
5.0
Troubleshooting Guide
Turn up thermostat.
Does the fan
blower turn on?
Is the power at the
heater 120V?
Find the source of the electrical problem between panel and heater.
No
Find the source of the
electrical problem
between panel and
external transformer.
Is there 120V on the
primary side of the
external transformer?
Is the power across
the left and middle
terminals of the
24V plug 24 volts?
External transformer
is faulty and must be
replaced.
The thermostat or wiring
is faulty and should be
replaced or repaired.
Find source of electrical problem between
the external transformer and thermostat.
24 Volts
Is there 24V on the
secondary side of the
external transformer?
Is there
24V to the
thermostat?
Yes
Yes
No
Yes
No
No
Yes
Yes
No
Is the power across the
left terminal of the 24V
plug and ground (screw
on the burner control
box) 24 Volts?
Is there 120V on
the primary side
of the internal
transformer?
Is there 24V on
the secondary
side of the
transformer?
Replace transformer.
Repair the wiring
between the trans-
former and the 24V
terminal plug.
Repair the wiring between power in and transformer.
Yes
No
No
Yes
No
No
Yes
Yes
Does the ignitor
warm up and
glow orange?
Is the ignitor
physically
damaged?
Replace ignitor.
Check voltage at ignitor
sequence (usually 5 to 15
seconds after power to
heater). Is it 120V?
Is the resistance through the
ignitor 50-400
Ω
?
Is the inlet or the outlet
of the unit plugged or
obstructed?
Remove obstruction.
No
Yes
Yes
No
No
No
Yes
Yes
No
Continued on page 51
No
Tr
o
u
b
le
sh
o
o
ti
n
g
w
it
h
R
el
ay
B
o
ar
d
No
Yes
5.0
Troubleshooting Guide
