Lennox Air Conditioner Error Code E600

E600 means the compressor has been cycled off due to utility load shedding. This occurs when 24VAC power is applied to the L and C terminals on the outdoor control board, signaling the unit to disable the compressor. It is not a mechanical fault. Normal operation resumes once the load shedding signal is removed.

A simple power reset will not clear E600 if the 24VAC load shedding signal is still present at the L and C terminals. The code will return as long as that voltage is being applied. The underlying signal source must be removed before the compressor can restart.

In most cases there is no repair cost, since E600 is triggered by a utility signal and resolves on its own when the event ends. If the error is caused by a faulty demand response module or wiring issue, repair costs can range from around $50 to $300 or more depending on the components involved and local labor rates.

To clear E600, the 24VAC signal at the L and C terminals on the outdoor control must be deactivated. If your utility company triggered a demand response event, the system should resume automatically when the event ends. If the error persists, inspect the wiring at those terminals and any connected demand response device or smart thermostat for faults.

No, E600 is not a safety-related fault. It is an intentional, controlled shutdown initiated by an external demand response signal. The system is operating as designed during a utility load shedding event. There is no risk of equipment damage from this condition.