Lennox · EL18KSLV Series Outdoor Units
The low pressure switch circuit has been detected as open for 60 seconds (after 5 minutes of compressor run time) or for 30 seconds during standby. This suggests a problem with system pressure or the switch.
Click steps to track your progress.
Power off the unit and check if the pressure switch connection is secure.
Use a multimeter to check if the low pressure switch terminal is short-circuited.
Check if the Electronic Expansion Valve (EEV) coil is fixed well.
Ensure the stop valve is open.
Use a multimeter to check the resistance of Tc, Te, and Ts.
Inspect the piping system for clogs and clean if necessary.