Fault Phenomenon: Schwing S500 air pressure is normal when cold. During continuous use of pneumatic tools (operating temperature), the air compressor does not build pressure, air pressure drops, and eventually brakes fail.

Troubleshooting Process:
– Checked air compressor belt: belt not slipping.
– Checked air lines: no obvious leaks.
– Checked unloading valve: valve actuates normally.
– Measured air compressor discharge temperature at operating temperature: found temperature too high.

Root Cause: The air compressor piston rings expand and seize due to heat, resulting in zero compression efficiency.

Required Parts: Air compressor repair kit.