Lennox Heat Pump Error Code Green OFF / Red SLOW Flash

This fault code indicates a low pressure fault condition where the low pressure switch tripped and the control board cycled the compressor off as a protective measure. The system detected refrigerant suction pressure below the acceptable minimum threshold. Common triggers include restricted coils, a malfunctioning fan motor, or low refrigerant charge. The compressor will remain off until the fault is cleared and conditions return to normal.

No, you should not attempt to bypass the fault or force the system to run while this code is active. The low pressure fault is a safety protection that prevents the compressor from operating under conditions that would cause internal damage such as oil starvation or overheating. Allow the system to remain off and address the root cause before resuming normal operation.

Repair costs vary widely depending on the cause. Cleaning coils and replacing an air filter may cost between $75 and $200 for a service call. Fan motor replacement typically runs between $200 and $500 including parts and labor. If the issue involves a refrigerant leak, costs can range from $300 to $1,500 or more depending on the severity of the leak, the amount of refrigerant required, and refrigerant type.

Start by checking both the indoor and outdoor units for any visible blockages such as debris, dirt buildup, or ice on the coils, and replace the air filter if it is dirty. Verify that both the indoor and outdoor fan motors are running and operating at proper speed. If airflow components appear normal, a licensed HVAC technician should connect manifold gauges to check refrigerant pressures and determine whether the system has a low charge or a refrigerant leak.

A reset may temporarily clear the fault and allow the system to restart, but if the underlying cause is not corrected the low pressure switch will trip again and the fault code will return. Resetting without diagnosing and fixing the root cause can lead to repeated compressor cycling, which may cause additional wear. Address the source of the low pressure condition first, then reset the system.