Instructions / Assembly
SERVICING
82
Diagnost ic/Status LED Codes
Co m fo rtNet™
Thermost a t Only
Symptoms of Abnormal Operation
(Legacy & ComfortNet™ Thermostat)
Green Ye ll ow Red Red Y1
Fault
De s cr i p ti on
Mes sage Code
Pos si ble Causes
Corrective Actions Notes & Cauti ons
• Air conditioner/heat pump may appear
to be operating normally.
• Integrated control module
diagnostic/status LED’s display the
indicated code.
OFF 9
Fl ashes
OFF ON if call
present;
OFF if no
call
• Low Pilot
Voltage
LOW
SECOND
VOLT
09 • Control detects secondary
voltage less t han 18 VAC.
• Transformer overloaded.
• Low line vol tage.
• Check fuse.
• Correct low secondary
voltage condition.
• Check transformer;
replace if needed.
• Turn power OFF prior
to repair.
• Fault will clear if
secondary voltage rises
above 21VAC.
• Replace with correct
replacement part(s).
• Co mpressor is off.
• Integrated control module
diagnostic/status LED’s display the
indicated code.
OFF ON ON ON if call
present;
OFF if no
call
• Comp Protector
Open
Not displayed
Not
displayed
• No current through run or
start windings.
• Compressor run wi nding
is open.
• Compressor not properly
wired to control.
• Faulty compressor wiring.
• Failed compressor run
capacitor.
• Faulty run capacitor
wiri n g.
• Check compressor;
repair/replace as
needed.
• Check wiring;
repair/replace as
needed.
• Check run capacitor;
replace as needed.
• Turn power OFF prior
to repair.
• Fault will clear after 1
no r mal cycle.
• Fault may be cleared by
cycling 24VAC to
control.
• Replace with correct
replacement part(s).