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Is 24 VAC available
at transformer?
Is 24 VAC present from terminal
THS2 to ground?
Is power available
to primary?
Are thermostat contacts and
limit control contacts closed?
Close
Contacts.
Check continuity of wiring to
determine why voltage does
not exist at THS2.
Is jumper installed
from terminal 5 to
ground?
Install
Jumper.
Replace
Transformer.
Determine why
voltage is not
present.
Open thermostat contacts for 30 seconds.
Close contacts and wait for prepurge (if applicable)
period. Is spark present now?
Turn off supply voltage.
Check high voltage cable.
Is it securely attached to
spark transformer?
Correct
Is condition of high voltage
cable good (not brittle,
burnt, or cracked)?
Replace
Is spark electrode
ceramic cracked
or is electrode
grounded out?
Replace
Johnson Control
module G760/761
Replace electrode
assembly.
System was in lockout.
Observe a complete operating
cycle to determine why
control locked out.
No Yes
No Yes
No Yes
No Yes
No Yes
No Yes
No Yes
No Yes
No Yes
h. Troubleshooting Flow Chart - Quick Reference...
First Visual Check
No Spark And System Does Not Work