Lennox International Inc. CBX40UHV02 Thermostat User Manual


 
icomfort Wi-Fit 7−Day Programmable Communicating Thermostat
Page 49
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
226 Critical (Furnace) The furnace high pressure switch is
stuck closed.
Check operation of high pressure switch closing during a heat call. Measure operating pressure
(inches w.c.). Inspect vent and combustion air inducer for correct operation and restriction. The
alarm/fault clears after the issue is corrected.
227 Moderate (Furnace) The furnace low pressure switch is
open in run mode.
Check pressure (inches w.c.) of low pressure switch closing during a heat call. Measure operating
pressure (inches w.c.). Inspect vent and combustion air inducer for correct operation and restriction.
The alarm/fault clears after the issue is corrected.
228 Moderate (Furnace) The furnace control is not able to cali-
brate the pressure switch.
Unable to perform pressure switch calibration. Check vent system and pressure
switch wiring connections. Check the drain trap for blockage. The alarm/fault clears after a success-
ful calibration.
229 Minor (Furnace) The furnace control has switched to
high fire ignition because the low fire pressure
switch did not close in the allowed time.
IFC switched to high fire ignition because low fire pressure switch did not close in allowed time. No
action is needed.
240 Moderate (Furnace) The furnace flame current is low. Check micro−amperes of the flame sensor using thermostat diagnostics. Clean or replace the flame
sensor. Measure voltage of neutral to ground to ensure good unit ground. The alarm clears after a
proper micro−amp reading has been sensed.
241 Critical (Furnace) The furnace flame is going out while
the furnace is heating.
Shut off gas. Check for a gas valve leak. Replace the gas valve if needed. The alarm/fault will clear
when a heat call ends successfully.
250 Moderate (Furnace) The furnace primary limit switch is
open.
Check for proper firing rate on furnace. Ensure there is no blockage in the furnace and the ductwork.
Check for proper air flow. If limit switch is not closed within 3 minutes, the unit will go into 1−hour
Watchguard mode. The alarm/fault will clear when a heat call ends successfully.
252 Moderate (Furnace) The furnace discharge air−tempera-
ture is high.
Check temperature rise, air flow and input rate. Check for dirty filters. The alarm/fault will clear when
a heat call ends successfully.
270 Critical (Furnace) The furnace is in Watchguard mode.
The furnace igniter cannot turn on the flame.
Check for proper gas flow. Ensure that igniter is lighting burner. Check flame sensor current. Check
for dirty filters. The alarm/fault will clear on successful ignition.
271 Critical (Furnace) The furnace is in Watchguard mode.
The furnace low pressure switch is open.
Check pressure (inches w.c.) of low pressure switch closing during a heat call. Measure operating
pressure (inches w.c.). Inspect vent and combustion air inducer for correct operation and restriction.
The alarm/fault will clear on successful ignition.
272 Critical (Furnace) The furnace is in Watchguard mode.
The furnace low pressure switch is open during
run mode.
Check operation of low pressure switch to see if it is stuck open during a heat call. Measure operat-
ing pressure (inches w.c.). Inspect vent and combustion air inducer for correct operation and restric-
tion. The alarm/fault will clear when a heat call ends successfully.
273 Critical (Furnace) The furnace is in Watchguard mode.
The furnace flame is going off during a heating
cycle.
Check micro−amperes of flame sensor using thermostat diagnostics. Clean or replace sensor. Mea-
sure voltage of neutral to ground to ensure good unit ground. The alarm/fault will clear when a heat
call ends successfully.
274 Critical (Furnace) The furnace limit switch has been
open for more than 3 minutes.
The system will go into Watchguard mode. Check firing rate and air flow. Check for blockage. The
alarm/fault will clear when a heat call ends successfully.
table continued on next page