Applicable Systems
S30 Thermostat
EL280 Furnace
XC21 Condenser
Merit Series
Symptoms
Indoor temperature sensor reading out of range; thermostat cannot maintain setpoint; comfort control degraded.
Possible Causes
- Temperature sensor open/short circuit
- Sensor wiring damaged
- Thermostat internal sensor failure
Troubleshooting Steps
- Step 1: Check indoor temp sensor resistance at thermostat
Resistance matches temp chart - Step 2: Inspect sensor wiring for damage
Wiring intact - Step 3: Verify sensor reading matches room temperature
Reading within 2C of actual - Step 4: Replace sensor if reading incorrect
New sensor reading accurate - Step 5: Clear code and verify thermostat operation
Thermostat maintains setpoint
How to Reset
Clear via thermostat menu: Settings > Diagnostics > Clear Faults.
Common Replacement Parts
- Lennox S30 Indoor Temperature Sensor
Frequently Asked Questions
- Q: Where is the temp sensor on Lennox S30?
Integrated in the S30 thermostat. Some installations use remote sensor (1032-R) for better placement. Check installation configuration.
Source: Lennox S30 Installation Manual
Category: HVAC Residential