42
UHM-DHM-SF-1H
Service Facts
YES
Is pressure greater
than pressure
switch labels?
See note #2
Replace pressure
switch. Check
operation.
User Interface
shows a
Pressure
Switch OPEN
User Interface
shows a
Pressure
Switch
CLOSED
Scroll through
User Interface to
View number 1 of
Last 4 Faults
Is the inducer
motor running?
NO
YES
Is voltage measured
at all 3 leads at the
inducer motor?
Measure from lead
to lead
Is 24 volts present,
measured across PS1,
(purple to yellow) PS2,
(brown to yellow) ?
See Note #1
Replace inducer
assembly. Check
operation.
YES
Disconnect electrical
power from the furnace
and remove 1 wire from
each pressure switch
Is continuity
measured
across PS1,
PS2, or PS3?
Replace pressure
switch. Check
operation.
YES
Pressure switch is
okay
NO
NOTE #1
24 volts = Open Switch
0 volts = Closed Switch
DEFINITION
An error has occurred with either PS1, PS2, or PS3.
The error will be reported, indicating that a pressure
switch is either opened or closed, contrary to normal
operating sequence
In most cases, the pressure switch is not the
problem
Note: Verify all wiring and pressure switch
tubing to pressure switches is correct per
the diagrams found in the Service Facts
Note #2
Measured pressure is
negative, greater than
refers to magnitude only.
3 Flash Fault LED
Cycle power to furnace, set
comfort control to heat, and
raise set-point 5 degrees
above actual room
temperature.
Each time power is interrupted to the furnace (ie. door
switch), the furnace will go through an inducer learning
routine to determine the most efficient speed to close
the pressure switches
Is Green LED
on IMDB
flashing?
NO
Replace Inducer
Motor Drive Board
Check operation
YES
Is 115V
present at
connector at
bottom of
IMDB?
NO
Replace Inducer
Motor Drive Board
Check operation
YES
Correct wiring.
Check operation
NO
Connect differential manometer per
instructions in Service Facts
YES
Measure
equivalent feet of
flue pipe
NO
Does equivalent
feet of pipe exceed
table in Installer’s
Guide
Check internal
venting system for
leaks. Correct as
needed
NO
Correct venting
system. Check
operation
YES
NO
PS1 & PS2
switches are okay
Allow 8 minutes of
operation for 100%
capacity in 24V
mode
Is 24 volts
present,
measured
across PS3?
See Note #1
PS3 is okay
NO
YES
Summary of Contents for ADHMB060BCV3VA
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