Lennox International Inc. G71MPP03 Thermostat User Manual


 
506920−01 09/12
Page 50
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.
Table 5. Alert Codes and Troubleshooting
Alert
Code
Steps to clearAlert TextPriority
275 Critical (Furnace) The furnace flame is out of sequence. The system will go into Watchguard mode. Shut off gas. Check for gas valve leak. The alarm/fault
will clear on next successful ignition.
276 Critical (Furnace) The furnace is not able to calibrate or
the high pressure switch opened or failed to
close in run mode.
The system will go into Watchguard mode. Check vent system and pressure
switch wiring connections. The fault/alarm will clear when the furnace calibrates itself successfully.
290 Critical (Furnace) There is a problem with the furnace
ignition circuit.
The system will go into Watchguard mode. Measure resistance of hot surface igniter. Replace the hot
surface ignitor it is not within specifications. The alarm/fault will clear on next successful ignition.
291 Critical (Furnace) The heating airflow is below the mini-
mum required level.
The system will go into Watchguard mode. Check for dirty filters and other air flow restrictions. Check
blower performance. The alarm/fault will clear when a heat call ends successfully.
292 Critical (Furnace / Air Handler) The (furnace or air−han-
dler) indoor blower motor will not start.
The system will go into Watchguard mode. Indoor blower motor unable to start. This could be due to
seized bearing, stuck wheel, obstruction etc. Replace motor or wheel if assembly does not operate or
meet performance standards. The alarm/fault clears after the indoor blower motor starts successfully.
294 Critical (Furnace) There is over current in the furnace
inducer motor.
The system will go into Watchguard mode. Check combustion blower bearings, wiring and amps.
Replace if does not operate or does not meet performance standards. The alarm/fault clears after
inducer current is sensed to be in−range after the ignition following the Watchguard mode or reset.
295 Minor (Furnace) The indoor blower motor is over heat-
ing.
Indoor blower motor over temperature (motor tripped on internal protector). Check motor bearings
and amps. Replace if necessary. The alarm/fault clears after blower demand is satisfied.
310 Critical (Furnace / Air Handler) There is a problem with
(furnace or air−handler) discharge air sensor.
Compare outdoor sensor resistance to temperature/resistance charts in installation instructions.
Replace sensor if necessary. The alarm/fault is cleared 30 seconds after fault is detected as recov-
ered.
311 Minor (Furnace) The heat firing rate has been reduced
to match available airflow (cutback mode).
Warning Only. Furnace blower in cutback mode due to restricted airflow. Reduce firing rate every 60
seconds to match available CFM. Check filter and duct system. To clear, replace filter if needed or
repair/add duct. 2−stage controls will reduce firing rate to 1st stage. The alarm/fault clears when a
heat call finishes successfully.
312 Minor (Furnace / Air Handler) The blower cannot pro-
vide the requested CFM due to high static.
Warning Only. Restricted airflow − Indoor blower is running at a reduced CFM (Cutback Mode − The
variable speed motor has pre−set speed and torque limiters to protect the motor from damage caused
by operating outside of design parameters (0 to 0.8" e.g.. total external static pressure). Check filter
and duct system. To clear, replace filter if needed or repair/add duct. The alarm/fault is cleared after
the current service demand is satisfied.
313 Minor (Furnace / Air Handler) The indoor and outdoor
unit capacities do not match.
Check for proper configuring in installation instructions. Alarm is just a warning. The system will
operate, but might not meet efficiency and capacity parameters. The alarm will clear after commis-
sioning is complete.
344 Critical (Furnace) Relay Y1 Failure Y1 relay failed; operation stopped. Alarm clears 300 seconds after Y1 input sensed OFF.
table continued on next page