Lennox MS8 SERIES Installation And Service Procedures page 59

Continued — 09 through 12 and 30 kBtu System Status and Error Codes — Indoor Character Display and Outdoor LEDs
Outdoor LED Displays
Indoor
(number of blinks)
Character
Display
Yellow Red
E5 5 OFF
E6 OFF OFF
FH OFF 4
F0 OFF OFF
F1 OFF OFF
F2 OFF OFF
F3 OFF 6
F4 OFF 4
F5 OFF 7
F6 OFF 3
F8 OFF 1
F9 OFF 2
HC 14 OFF
H1 2 OFF
H3 8 OFF
Error Description
Green
Compressor
over-current
OFF
protection
Communication
failure between
OFF
indoor unit and
outdoor unit
Anti-freezing upper
and lower limit
OFF
range
Indoor coil is
OFF
gathering refrigerant
Indoor ambient
sensor (RT1) open
OFF
or short circuited
Indoor coil sensor
(RT2) open or short
OFF
circuited
Outdoor ambient
sensor (RT4) open
OFF
or short circuit
Outdoor coil sensor
OFF (RT3) open or short
circuit
Discharge line
OFF
sensor (RT5) error
Compressor over­
OFF
load limit issue
High current limit
OFF
issue
Discharge line
temperature too
OFF
high
Power factor
correction
OFF
protection
Defrosting (heat
OFF
pump only)
Compressor
overload protection
OFF
sensor (CT1,2)
malfunction.
Page 59
System Status
All system functions are
terminated except indoor fan.
All system functions are
terminated after three-minute
delay except indoor fan.
Compressor will run at reduced
speed until temperature increases.
All system functions are
terminated except indoor fan.
Cooling and dehumidification
modes will continue to operate as
well as indoor fan. Unit will not
operate in heating mode.
All system functions are
terminated except indoor fan.
All system functions will continue
to run for 3 minutes, then
terminate. Indoor fan will continue
to run.
Normal operational state with
compressor speed automatically
adjust for operational conditions.
System will continue to operation
at reduced compressor speed until
issue is corrected.
System will continue to operate at
reduce compressor speed until
issue is corrected.
System will continue to operate at
reduce compressor speed until
issue is corrected.
Normal operation
All system functions are
terminated except indoor fan.
Troubleshooting for Possible
Causes
S Check for locked compressor rotor
due to excessively high ambient
temperature.
S Check for restricted refrigerant flow
due to blocked capillary tubing.
S Check outdoor unit to make sure
that coil is not blocked.
S If error is displayed on outdoor unit,
check communications cable / wire
at indoor and outdoor controls to
verify proper connection. See unit
information manual for further
information.
S Wait for temperature to increase
above 42.8ºF (6ºC), then recheck
operation status.
S Pump refrigerant into outdoor unit.
Check 2-way shut-off valve in small
line to see if it is closed or if flow is
restricted. Correct, if necessary.
S Check sensor to ensure that it is in
acceptable range.
S Check sensor for proper resistance.
S Replace sensor if shorted, open or
out-of-calibration.
S Check sensor to ensure that it is in
acceptable range.
S Check sensor for proper resistance.
S Replace sensor if shorted, open or
out-of-calibration.
S Check sensor for proper resistance.
Sensor should be in acceptable
range. Replace sensor if shorted,
open or out-of-calibration.
S Check outdoor ambient air
temperature. Could be too high.
S Check for locked compressor rotor.
S Check for blocked refrigeration
circuit (capillary tubes for example).
S Check for blocked or restricted
outdoor air flow. Clear, if necessary.
S Check for low refrigerant charge.
S Check for low or high input voltage.
Correct if necessary. Could be too
high.
S Check discharge line temperature.
Correct if to high.
See unit information manual for fur­
ther information.
Normal defrost operation.
S Check for proper wiring connec­
tions and loose wires at outdoor
control (CT1, 2) input plug.
S Check for continuity across over­
load protection sensor terminals
mounted at top of compressor.
Corp. 1244-L9