Lennox Heat Pump Error Code DS2 OFF / DS1 ON

This fault code means the low pressure switch (DS1) has tripped five times within a single Y1 demand cycle, triggering a compressor lockout (DS2 OFF). The control board tracks these repeated low pressure events and locks out the unit to protect the compressor from damage caused by running at insufficient refrigerant pressure. A technician will need to diagnose the root cause before the system can resume normal operation.

Some basic checks, such as inspecting air filters, clearing debris from outdoor coils, and verifying airflow, can be performed without special tools. However, checking refrigerant charge and operating pressures requires certified refrigerant handling equipment and EPA Section 608 certification. Any work involving the refrigerant circuit must be performed by a licensed HVAC technician.

Repair costs vary widely depending on the cause. Clearing a blocked coil or replacing a filter may cost very little, while diagnosing and repairing a refrigerant leak with recharge can range from a few hundred to over a thousand dollars. Replacing a failed low pressure switch is typically in the range of fifty to two hundred dollars in parts plus labor. Compressor replacement, if the unit was run extensively in a low pressure condition, can cost significantly more.

A power reset may temporarily clear the lockout and allow the unit to restart, but it will not fix the underlying problem. If the condition that caused low pressure is still present, the low pressure switch will trip again and the system will return to lockout. Resetting repeatedly without diagnosing the cause risks compressor damage and should be avoided.

No. The lockout is a protective measure designed to prevent compressor damage. Attempting to bypass the low pressure switch or repeatedly resetting the system without addressing the fault can result in compressor failure, which is one of the most expensive repairs on a heat pump. Leave the unit off until the fault has been properly diagnosed and corrected.