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DEFINITION
An error has occurred with the PS2 indica ng that the pressure
switch is open when it should be closed.
In most cases, the pressure switch is not the problem.
NOTE: Verify pressure switch wiring and tube rou ng
are correct.
PS2 is closed & pressure
S8XB-SVX001-1C-EN
Cycle power to the furnace and call for 2 stage heat.
1 stage sequence must be func onal before 2 stage can
become ac ve. Insure the inter-stage delay is not in
process when W1 - W2 signals are applied simultaneously
Replace Inducer
YES
Assembly
NO
switch is okay.
Check PS hose rou ng and verify
flue piping has no obstruc on
3.4 Fault Code
nd
nd
Is ~120VAC
measured from BK
NO
to WH on the
inducer motor?
YES
Is 24 volts present,
measured across PS2
(brown to yellow)?
See Note #1
YES
Is pressure measured
greater than
YES
pressure switch
label?
See Note #2
NO
T T r r o o u u b b l l e e s s h h o o o o t t i i n n g g
Note #1
24 volts = Open Switch
0 volts = Closed Switch
Note #2
Measured pressure is
nega ve, greater than refers
to magnitude only.
Replace IFC
Replace pressure switch.
Check opera on.
67
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