221
Moderate
Lennox · HVAC Systems (AC, Furnaces & Heat Pumps)
Gas Valve Relay Failure
Quick Answer
Error code 221 on your Lennox HVAC Systems (AC, Furnaces & Heat Pumps) means: Gas Valve Relay Failure. This is usually fixable — see the step-by-step guide below.
Likely Causes
How to Fix It
1
Verify 24VAC is present at the gas valve leads during a call for heat
2
Check the gas valve coil resistance (typically 150-600 ohms)
3
Inspect wiring between the control board and gas valve for damage or loose connections
4
If the relay is clicking but no voltage reaches the gas valve, the control board needs replacement
5
Gas valve and control board replacement should be performed by a licensed HVAC technician
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Control board
Gas valve
Wiring harness
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