30
P/N 032498h
Troubleshooting
Symptom
Possible Cause
Solution
Display is blank
The thermostat does not have power.
Check the wiring to confirm that Common
(Black) and V+ (Red) are connected to a
24–36 V
-
power supply.
E0 shown on the master thermostat
The thermostat temperature sensor is not functioning
properly.
Contact Customer Assistance.
E0 shown on the companion thermostat
A companion thermostat will show E0 if the
temperature sensor for that zone is missing.
Check the error code on the master thermostat.
E1 shown on the master thermostat
Wiring issue between the thermostat and the HVAC
controller or HVAC controller does not have power.
Ensure that the HVAC controller communication
link is wired correctly and isolated from all other
connections and that the HVAC controller has
power.
The incorrect HVAC controller or Modbus address was
selected.
Enter HVAC controller selection mode and
select the correct HVAC controller and Modbus
address.
E1 shown on the companion thermostat
Wiring issue between the processor and HVAC
controller (if HVAC controller is connected to the
processor).
Check the wiring between the processor and
HVAC controller.
The master thermostat (connected to the HVAC
controller) is disconnected from the processor.
Ensure that the QS link between the master
thermostat and the processor is wired correctly.
E2 shown on the display
Remote temperature sensor is malfunctioning or
misconfigured.
Check the wiring between the sensor and the
HVAC controller and confirm configuration.
E3 shown on the display
Changeover sensor malfunctioning or misconfigured
(applicable only for 2-pipe systems).
Check the wiring between the sensor and the
HVAC controller and confirm configuration.
E4 shown on the display
QS link wiring error or the thermostat did not get a
temperature reading from the system.
Contact Customer Assistance
E5 shown on the display
Incorrect HVAC controller or thermostat model.
Ensure that SMC55-RESI and HQWT-T-HW are
being used.
E6 shown on the display
Slab temperature sensor for underfloor heating is
missing, malfunctioning, or misconfigured.
Check the wiring between the slab sensor and
the HVAC controller and confirm configuration.
System is not heating / cooling.
The HVAC controller or HVAC equipment may not
have power.
Ensure that the HVAC controller and HVAC
equipment have power and are correctly wired.
Consult an HVAC professional if the issue
persists.
System is not heating / cooling as expected
Mounting location of the thermostat is incorrect.
Refer to Mounting section of the thermostat
installation guide.
Wiring issue between the HVAC controller and the
HVAC system.
Check the Wiring section in the thermostat
installation guide.
The HVAC system may not have power.
Ensure that the HVAC system has power.
