22
TROUBLESHOOTING INFORMATION: UNITARY DIAGNOSTIC CODES
Diagnostic/Status LED Codes
ComfortNet™
Thermostat Only
Symptoms of Abnormal
Operation (Legacy &
ComfortNet™ Thermostat)
Green Yellow Red Red Y1
Fault
Description
Message Code
Possible Causes
Corrective Actions Notes & Cautions
x Air conditioner/heat pump may
appear to be operating normally.
x Integrated control module
diagnostic/status LED’s display
the indicated code.
OFF 9
Flashes
OFF ON if call
present;
OFF if no
call
x Low Pilot
Voltage
LOW
SECOND
VOLT
09
x Control detects
secondary voltage less
than 18 VAC.
x Transformer
overloaded.
x Low line voltage.
x Check fuse.
x Correct low
secondary voltage
condition.
x Check transformer;
replace if needed.
x Turn power OFF
prior to repair.
x Fault will clear if
secondary voltage
rises above 21VAC.
x Replace with correct
replacement part(s).
x Compressor is off.
x Integrated control module
diagnostic/status LED’s display
the indicated code.
OFF ON ON ON if call
present;
OFF if no
call
x Comp
Protector
Open
Not
displayed
Not
displayed
x No current through run
or start windings.
x Compressor run
winding is open.
x Compressor not
properly wired to
control.
x Faulty compressor
wiring.
x Failed compressor run
capacitor.
x Faulty run capacitor
wiring.
x Check compressor;
repair/replace as
needed.
x Check wiring;
repair/replace as
needed.
x Check run
capacitor; replace
as needed.
x Turn power OFF
prior to repair.
x Fault will clear after
1 normal cycle.
x Fault may be
cleared by cycling
24VAC to control.
x Replace with correct
replacement part(s).
To Next Page
Loading...
