For systems with modulating load controls, the air capacity control system may not be adjusted properly. Follow the manufacturer's recommendation for adjustment of the modulation system. In reciprocating compressors, another cause may be worn or broken valves or the wrong setting on your air pressure switch. Check the valves and repair or replace as required. Follow the manufacturer's recommendations for setting the air pressure switch. If none of the above solves the problem, the low-pressure problem may be caused by an undersized compressor. You may require additional capacity (CFM) to maintain the desired system pressure.