my craftsman 1HP 7 GAL air compressor is very new, but it wont build up air after reaching 25 lbs. i checked the piston, rings, reed valves, and replaced the check vavle. i cant find anything that looks bad. i am ready to give up. can someone please give me some advice to what i my be missing or over looking. THANK YOU!!
The firs thing I note is that the compressor is/was "very new", then you state that you have taken it apart to check internal components--probably voided any warranty there. Items I would go looking for in this order would be: 1)
Is the compressor actually compressing air? 2)Cracked or broken reed valve, 3) Check valve not working properly. Is this one of the little red units? UH-OH! Try running the unit with the drain valve on the bottom wide open. It will/should make a loud whistling noise which will build up in intensity with air pressure. Another option would be to take the line loose as it connects to the check valve and run the unit for a minute or so to see/listen if compressed air is coming from the compressor unit via the tube that goes to the tank at a somewhat constant force. DO NOT put your thumb over this tube-it will push air/oil into your pores. For some reason these units are notorious for "back-pressure" problems, meaning that the more pressure in the tank the harder it is to push more air into the tank. That sounds like a check valve problem but Sears stated that there was no problem when these first came out. Blowing backwards through the check valve is not a good way to test them. They need more pressure for testing. IF all I suggested does not help, and the new check valve does not help, I'm stumped. David