YES
YES
Is pressure greater
than pressure switch
label?
See Note #2
Replace pressure switch.
Check opera!on.
Is the inducer
motor running?
Is 24 volts present,
measured across PS1
(orange to yellow)?
See Note #1
Note #1
24 volts = Open Switch
0 volts = Closed Switch
DEFINITION
An error has occurred with the PS1 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.
PS1 Open errors can occasionally occur when wind gusts occur.
The IFC will a"empt to close both PS1 by increasing the voltage to
the inducer motor
Note #2
Measured pressure is
nega!ve, greater than refers
to magnitude only.
3.2 Fault Code
NO
Cycle power to the furnace
and call for 1
st
stage heat.
NO
Possible Causes:
PS hose, flue piping for obstruc!on
and/or confirm vent size is correct
NO
NO
Pressure switch
is okay.
Is voltage measured
from
RD- WH
BK-RD
BK-WH
at the inducer
motor
Replace inducer
assembly
YES
Is PS1 oriented
correctly for the
applica!on?
Correct orienta!on
See this document
NO
Verify no voltage at IFC
Replace IFC
NO
Does the igniter
glow within 60
seconds?
PS1 is closed Yes
YES
NO
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