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All installations and services must be performed by qualified service personnel.
32
Yes
Set thermostat subbase to "HEAT"
Does thermostat make contact?
Does a "call for
heat" initiate an
ignition cycle?
No
Yes
Is room temperature
above 90 deg. F?
Yes
Wait for room air to cool.
Yes
Turn thermostat setting
above room temp.
Replace thermostat
Is there 120 VAC
across lines L1 & L2?
Check input power. Reset circiut
breaker, or replace blown fuse in
disconnected switch.
No
Is the control transformer
(GMC) or oil primary control
(OMC) receiving 120 VAC?
Have either of the
high limit thermostats
activated?
No Yes
No
Yes
Turn power
switch "on".
Wait for furnace to cool.
Look for cause(s) of high
limit activation,eg. low
airflow, over-firing,
blocked flue,etc..
Correct any
abnormal conditions.
OMC/GMC TROUBLESHOOTING FLOWCHART
No
No
Yes
Yes
No
Is the power switch "off"?
No
Is room temperature above
thermostat setting?
With power on,measure
voltage across the aux.
high limit thermostat N.C.
contact to L2. If not 120 VAC,
replace aux. high limit
thermostat. Else,replace
high limit thermostat.