I have a customers Atlas Copco XAS/50 air compressor in the shop at the moment and their complaint is that it cuts out. I gave it a run to see and the engine reduces speed to idle when it hits the pressure setting but the compressor doesn't cut out so it stalls the engine unless I crack the ball valve to vent the tank and keep the engine at full throttle. I can't find any info on how the control system works on these nor where to start looking. Any advice would be appreciated!
Some pictures
From what I understand about most all compressors, if more air is allowed to enter the screw, then it will put load to the engine that is not putting in more fuel to keep it running. Maybe you have air leaking into compresssor causing load. It will probably have rods or a valve to adjust. Possibly the screw is sucking air into itself through the rotor seals. Simon C
That big valve on top of the blower, that's basically an unloader. It's common for the diaphragm to tear. I'd start there.