506920−01 09/12
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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 clear
Alert Text
Priority
180
Critical
(Furnace / Air Handler / Outdoor Unit) The ther-
mostat has found a problem with the
(furnace,
air−handler or outdoor unit)
outdoor sensor.
In normal operation after control recognizes sensors, the alarm will be sent if valid temperature
reading is lost. Compare outdoor sensor resistance to temperature/resistance charts in unit installa-
tion instructions. Replace sensor pack if necessary. At the beginning of (any) configuration, furnace
or air−handler control will detect the presence of the sensor(s). If detected (reading in range), ap-
propriate feature will be set as ’installed’ and shown in the ’About’ screen. The alarm/fault will clear
upon configuration, or sensing normal values.
200
Critical
(Furnace) The furnace rollout limit switch is
open.
Correct the cause of rollout trip. Reset rollout switch. Reset power to clear. Test the furnace opera-
tion. The alarm/fault clears after the furnace rollout switch is closed.
201
Critical
(Furnace / Air Handler) The system has lost
communication with the
(furnace or air−handler)
indoor blower motor.
Lost communication with indoor blower motor. Possible causes include: power outage, brown−out,
motor not powered, loose wiring, condensation on air handler control without cover on breaker.
Problem may be on control or motor side. Cleared after communication is restored.
202
Critical
(Furnace / Air Handler) The unit size code for
the
(furnace or air−handler)
and the size of blow-
er motor do not match.
Incorrect appliance unit size code selected. Check for proper configuring under Unit Size Codes for
Furnace/Air Handler on configuration guide or in installation instructions. The alarm/fault clears after
the correct match is detected following a reset. Remove the thermostat from the system while apply-
ing power and reprogramming.
203
Critical
(Furnace / Air Handler) The unit size code for
the
(furnace or air−handler)
has not been se-
lected.
No appliance unit size code selected. Check for proper configuring under: Unit Size Codes for Fur-
nace/Air Handler on configuration guide or in installation instructions. Critical Alert. The alarm/fault
clears after the correct match is detected following a reset. Remove the thermostat from the system
while applying power and reprogramming.
204
Critical
(Furnace) There is a problem with the furnace
gas valve.
Check gas valve operation and wiring. The alarm/fault clears after the issue is corrected.
205
Critical
(Furnace) The furnace gas valve relay contact
is closed.
Check wiring on control and gas valve. The alarm/fault clears after the issue is corrected.
206
Critical
(Furnace) The furnace gas valve 2nd stage
relay is faulty.
Furnace will operate on 1st stage for the remainder of the heating demand. The alarm/fault will clear
after the issue is corrected. If unable to operate 2nd stage, replace control.
207
Critical
(Furnace) The furnace hot surface igniter is
open.
Measure the resistance of hot surface igniter. Replace the it if it is not within the specified range
found in IOM. The alarm/fault clears after the issue is corrected.
223
Critical
(Furnace) 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 clears after the issue is corrected.
224
Critical
(Furnace) The furnace low pressure switch is
stuck closed.
Check operation of low pressure switch to see if it is stuck closed for longer than 150 seconds 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.
225
Critical
(Furnace) The furnace high pressure switch is
failing to close.
Check pressure (inches w.c.) 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.
table continued on next page
