Lennox iComfort G71MPP-03 Setup Manual page 30

Table 10. Alert Codes and Troubleshooting
Alert
Priority Alert Text
Code
(Outdoor Unit) The compressor rotor is
locked up. This could be due to a short cir
404 Critical
cuiting of the run capacitor, seizing of the
bearings or excessive liquid refrigerant etc.
(Outdoor Unit) The compressor circuit is
405 Critical open. This could be due to a power discon
nection, open fuse etc.
(Outdoor Unit) The required amount of cur
406 Critical rent is not passing through the start current
transformer.
(Outdoor Unit) The required amount of cur
407 Critical rent is not passing through run current trans
former.
(Outdoor Unit) The compressor is running
408 Critical
continuously.
(Furnace / Air Handler / Outdoor Unit) The
secondary voltage for the (furnace, air-hand
ler or outdoor unit) has fallen below 18VAC. If
409 Moderate
this continues for 10 minutes, the thermostat
will turn off the (furnace, air-handler or out
door unit).
(Outdoor Unit) The outdoor unit pressure is
410 Moderate
below the required limit.
(Outdoor Unit) The low pressure switch has
opened 5 times during one cooling cycle. As
411 Critical
a result, the thermostat has shutdown the
outdoor unit.
(Outdoor Unit) The outdoor unit pressure is
412 Moderate above the required limit. The system will shut
down.
(Outdoor Unit) The high pressure switch has
opened 5 times during one cooling cycle. As
413 Critical
a result, the thermostat has shutdown the
outdoor unit.
(Outdoor Unit) The discharge line temperat
414 Critical ure is higher than the recommended upper
limit of 279ºF.
(Outdoor Unit) The discharge line temperat
415 Critical ure has been consistently higher than the
recommended upper limit of 279ºF.
(Outdoor Unit) The outdoor coil sensor is
either open, short-circuited or the temperat
416 Critical ure is out of sensor range. As a result the
outdoor unit control will not perform any de
frost tempering.
(Outdoor Unit) The outdoor unit sensor is
either open, short-circuited or the temperat
417 Critical ure is out of sensor range. As a result the
outdoor unit control will not perform any de
frost tempering.
(Damper Control Module) The damper con
trol discharge air temperature sensor is either
Moderate open, short-circuited or the temperature is
417
/ Critical out of sensor range. As a result the outdoor
unit control will not perform any defrost tem
pering.
(Outdoor Unit) There is a faulty "W" output
418 Moderate
circuit.
(Outdoor Unit) The "W" output on the outdoor
unit has reported more than 5 errors. As a
419 Critical
result, the system has shutdown the outdoor
unit.
(Air Handler / Equipment Interface Module) )
420 Critical The heat pump defrost cycle has taken more
than 20 minutes to complete.
(Outdoor Unit) The "W" output terminal on the
421 Critical
outdoor unit is not wired correctly.
Compressor top cap switch exceeding
422
Moderate
thermal limit.
Moderate /
423 The inverter has detected a circuit problem.
Critical
507152-01
Critical alerts are displayed on Home (user) screen, in the Homeowner alert button, and in the
Installer alert button. Minor and Moderate alerts are found only in the Installer alert button.
Steps to clear
Compressor rotor locked up due to run capacitor short, bearings are seized, excessive liquid
refrigerant, etc. (NOTE: May need to install hard start kit). Clears the error after 4 consecutive
normal run cycles or after power reset.
Compressor circuit open (due to power disconnection, open fuse, etc.) Clears the
error after 1 normal compressor run cycle.
Required amount of current is not passing through Start current transformer. Clears the error
after current is sensed in START sensor, or after power reset.
Required amount of current is not passing through Run current transformer. Clears the error
after current is sensed in RUN sensor, or 1 normal compressor run cycle, or after power reset
Compressor runs continuously. Clears the error after 1 normal compressor run
cycle or after power reset.
Secondary voltage is below 18VAC. After 10 minutes, operation is discontinued.
Clears the code after voltage is higher than 20 VAC for 2 seconds or after power
reset.
Unit pressures are below the lower limit. Pressure switch opens at 40 psig (system shuts down)
and closes at 90 psig (system restarts).
Open low pressure switch error count reached 5 strikes. Check system charge using approach
and sub cooling temperatures. Reset by putting outdoor unit control in test mode or resetting
low voltage power.
Unit pressure is above the upper limit. System is shut down. The high pressure switch for
HFC410A will open at 590PSIG and close at 418PSIG. Confirm that the system is properly
charged with refrigerant. Check condenser fan motor, TXV, indoor unit blower motor, stuck
reversing valve or clogged refrigerant filter. Confirm that the outdoor unit is clean. The alarm
clears after the pressure switch closes or a power reset
Open high pressure switch error count reached 5 strikes. Check system charge
using approach and sub cooling temperatures. Check outdoor fan operation. Check for dirt or
debris blocking air flow to outdoor unit. Reset by putting outdoor unit control in test mode or
resetting low voltage power.
Discharge line temperature is > 279ºF. Make sure coil is clean and airflow unobstructed in and
out of condenser. Check system operating pressures and compare to unit charging charts in
installation manual. Clears after discharge temperature is < 225ºF.
Discharge line high temperature error count reached 5 strikes. Make sure coil is clean and
airflow unobstructed in and out of condenser. Check system charge using approach and sub
cooling temperatures. Reset by putting outdoor board in test mode or resetting low voltage
power.
Sensor being detected open or shorted, or temperature is out of sensor range.
Outdoor unit control will not perform demand or time/temperature defrost operation. (System
will still heat or cool.) Clears when outdoor unit control detects proper sensor readings.
Outdoor unit control detects open or shorted sensor, or temperature that is out of sensor range.
Critical Alert after 10 minutes. Reset by replacing sensor. This fault is detected by allowing the
unit to run for 90 seconds before checking sensor resistance. If the sensor resistance is not
within range after 90 seconds, the board will count one fault. After 5 faults, the board will lock
out. Check for proper sensor reading and attachment to line. Replace if out-of-specifications.
The damper control module detects open or shorted discharge sensor, or temperature that is
out of discharge sensor range. Check the resistance of the discharge sensor and compare to
temperature resistance chart - replace if needed. Reset by replacing the discharge sensor.
This fault is detected by allowing the unit to run for 90 seconds before checking discharge
sensor resistance. If the discharge sensor resistance is not within range after 90 seconds, the
control will count one fault. After 5 faults, the control will lock out. Check for proper sensor
reading and attachment to line. The alarm clears after a power reset.
Faulty W output circuit.
W output hardware fault count reached 5 strikes.
Defrost cycle lasts longer than 20 minutes. Check heat pump operation. Cleared
when W1 signal is removed. Applicable only in communicating mode with non-communicating
heat pump.
Voltage sensed on W output terminal when Y1 out is deactivated.
Check condenser fan motor, TXV, indoor unit blower motor, stuck reversing valve or clogged
refrigerant filter. Automatically clears when error is corrected.
Control will lockout after 10 strikes within an hour. To clear disconnect power to outdoor unit
and restart.
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table continued on next page
7/2013