e1
Moderate
Lennox · HVAC Systems (AC, Furnaces & Heat Pumps)
High/Low Pressure Lockout
Quick Answer
Error code E1 on your Lennox HVAC Systems (AC, Furnaces & Heat Pumps) means: High/Low Pressure Lockout. This is usually fixable — see the step-by-step guide below.
Likely Causes
How to Fix It
1
Check both the high-pressure and low-pressure switches for an open condition
2
Clean the outdoor condenser coil with a garden hose and approved coil cleaner
3
Verify the condenser fan motor is operating properly
4
Check the air filter and indoor coil for restrictions causing low suction pressure
5
A licensed HVAC technician must connect gauges to diagnose pressure issues and handle refrigerant per EPA regulations
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
Refrigerant (R-410A)
Condenser fan motor
High/low pressure switch
TXV valve
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