LPS
Heil
Low-Pressure Switch Open
Heil outdoor unit LED indicates LPS; compressor will not run
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Low refrigerant charge from leak, Severely restricted airflow across indoor coil, Faulty low-pressure switch, Blocked or frozen evaporator coil
How to Fix / Troubleshooting
Safety first: Turn off power to both indoor and outdoor units. Do not attempt to bypass safety switches.
- Step 1 – Check filter and vents: Replace dirty filters and open all supply/return vents to restore airflow.
- Step 2 – Inspect for ice: Look at the indoor coil and suction line. If iced, turn system OFF and fan ON to thaw completely (may take several hours).
- Step 3 – Reset and test: After thawing, restore power and call for cooling. If LPS clears and cooling returns, monitor operation.
- Step 4 – Leak suspicion: If LPS returns, the system may be low on refrigerant. A licensed technician must locate and repair leaks, then evacuate and recharge the system.
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Repair Difficulty
Professional Required
5/5
Required Part
Low-Pressure Switch
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