Repair Parts; G21Q Troubleshooting - Lennox G21Q Series Installation Instructions Manual

20- - Lift heat train from unit.
21- - Backflush heat train with a soapy water solution or
steam clean.
IMPORTANT
If unit is backflushed with water, make sure all wa-
ter is drained from heat train before replacing.
5(3$,5 3$576 /,67
The following repair parts are available through independent Lennox dealers. When ordering parts, include
the complete furnace model number listed on the unit rating plate. Example: G21Q3- -60- -1.
CABINET PARTS
Top access panel
Blower panel
Vestibule panel
Control box cover
CONTROL PANEL PARTS
Transformer
Indoor blower relay
Fan Timer Control
*4 7528%/(6+227,1*
LIT
Control should operate properly. Pro-
ceed to “UNIT WILL NOT RUN”- -GAS
CHECKS AND SPARK CHECKS to rule
out other possibilities.
If 24 VAC is present between JP72- -4
and Common and LED is not lit, reset
power to control. If control still does
not operate, replace control.
BLOWER PARTS
Blower wheel
Motor
Motor mounting frame
Motor capacitor
Blower housing cut- -off plate
Blower housing
GC3 AND G891 IGNITION CONTROL
TROUBLESHOOTING FLOW CHART
START HERE
IS GREEN DIAGNOSTIC LED LIT?
Does control A3 have 24VAC
supplied between pins JP72- -4
and Common?
YES
22- - Reverse above steps to replace heat exchanger as-
sembly. Be sure rubber seal pad is in place on air
pipe and that ground wire on gas valve is put back
on the upper- -right air decoupler box mounting stud.
NOT LIT
Turn off unit power at disconnect for at least 3
seconds. Then turn power back on. Allow 3 se-
conds for control to power- -up. Control should
operate properly, proceed to “UNIT WILL NOT
RUN”- -GAS CHECKS AND SPARK CHECKS to rule
Proceed to
ELECTRICAL CHECKOUT.
3DJH 
HEATING PARTS
Heat exchanger assembly
Gas orifice
Gas valve
Gas decoupler
Gas flapper valve
Purge blower
Air intake flapper valve
Primary control
Ignition lead
Spark plug ignitor
Flame sensor lead
Flame sensor
FLASHI
NG
out other possibilities.
NO