I have a kobalt oilless 15 gal. air compressor that only builds to 65 psi and wont shut off,piston seems fine,no funky noises,heard it could be check valve,took it off no obstructions,thinking bud pressure switch or maybe need regulator rebuild?ank tests recommended,model#215902
The problem lies in the pump itself. One or more of the compression components. Either the piston (compression) ring is defective (most likely) or one or more of the reed valves are damaged. This is the only reason the unit would not build to pressure, barring a large, obvious air leak somewhere else.
Unfortunately the piston ring isn't sold for this model, only the valves.