Hi
according to EAS tech info i have read the system should be up to full pressure within 8 mins & at this point the compressor should have stopped. also if the vehicle was on bump stops the pressure in tank from previous running of compressor will be able to lift the vehicle to desired ride height instantly. If not then thre is most likely a worn piston teflon seal in the compressor pump which is easly replaced, also the pump cilinder gets worn so it is better to replace the piston with cam, cilinder, bottom seal ring within compressor pump all in one & you can get them from ebay cheap. also the valve block seals & pipe o rings are very problamatic & in my case i replaced all of them. it took me about 4 hours to do all of the above including removal & refit pump & valve block into car after taking it in house to repair.