Is 24 volts present,
measured across PS2?
(brown to yellow)?
See Note #1
Note #1
24 volts = Open Switch
0 volts = Closed Switch
3.3 Fault Code
Cycle power OFF, then ON to
the furnace
Is PS2 oriented
correctly for the
applica!on?
NO
YES
Correct orienta!on
See this document
NO
Replace pressure
switch
Verify wiringYES
DEFINITION
An error has occurred with the PS2, indica!ng that the
pressure switch is closed when it should be open.
In most cases, the pressure switch is not the problem.
NOTE: Verify pressure switch wiring and tube rou!ng are
correct.
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