20 Most Recent AO Smith 2 Hp Spl 3450rpm M56 Frame 115/230 Volts Replacement Air Compressor Motor Electric Motor No.B381 Questions & Answers

it sounds like the unloader is not working so it's trying to start with to much head pressure. One cause is a bad check valve another is a bad pressure switch. Those are the more common problems.

Red and Black should each be connected to the individual power legs, for 230 V operation. The white wire should be connected to ground.

Diagram for aosmith motor b381 is here: http://www.electricmotorwarehouse.com/IMAGES/B381_connection.htm

However, I believe that this motor will be more efficient at 230v depending on load conditions. At 115v this motor will draw more amps and tend to run hot, but situation rules. Enjoy

There is not a point setting for air compressors. The pressure switch can be adjusted. Remove the cover from the pressure switch. Adjust the nut tighter for a higher cut off pressure or looser for a lower cut off pressure. It sounds like the compressor is trying tostart under load. If the unloader valve is not working, the compressor will draw excess amperage and do what you describe. The unloader valve releases the pressure in the cylinder at the end of the run cycle so the compressor can start the next run cycle under no load.

try running up this motor when its not installed on the compressor,, if it still blows the trips the motor is faulty,, if it runs ok, but hums when reconted to the compressor the compressor if far to tight for the motor to turn the compressor,,,you can not reset the points in a breaker trip they trip at a set curent if the motor is pulling more amps than the trip is set for it will trip the trip to turn off the curent, the motor will pull far more amps than it should if its over loaded thats why its humming its trying to spin up it but cant so it just keeps pulling more and more amps till the trip cuts out

Thank you for posting your question here on Fixya.com.

A 2 HP motor is usually only going to connect to 230V 1~ because of the high amp draw if ran on 115V. The motor itself should say 115/230 V and then would also read 24/12 Amp. It seems based upon your post it is not a dual voltage motor, likely for the reason I stated. You can not reconnect the motor from series to parallel because the winding connections to the leads are not brought out for you to do so. Otherwise it would be labeled for 115/230. You can of course try to get a 2 HP 115 volt rated motor or try to reconnect a circuit where you wish to use the compressor to bring the 230 V to it. In the long run, you would be better off running the motor on 230V.

If this answer does not fix your problem, please comment with additional details prior to rating the answer. Positive feedback is appreciated once your problem is solved!

John

Sounds like you have this plugged into a circuit that has to much draw on it,or you are using an extension cord, don't use an extension cord, and see if you can figure what else is on the circuit, if nothing else is on it and you have the full 20amps then something is wrong with the motor.

First, take the plate where the wires connect to the motor off, and the solution is normally found in the dust cap for the wiring. If not there, go to the AO Smith website with your motor model number and there should be instructions on which of the numbered leads to group together in order to reverse the rotation. Don't worry- it's easy. Don't forget to unplug everything before changing these wires around.

Our 2 HP Speedaire horizontal tank compressor is rated 115 / 230 volts at 24 / 12 amps, respectively. This means at 115 volts, a 30 amp circuit breaker is the bare minimum. That also means that the wiring should be #10 copper wires for short runs, but the next size up; #8 copper wires would be better connected to a 40 amp circuit breaker. Running at 230 drops the amperage requirement by half, to 12. A #14 copper wire is minimum for short runs with a double pole 15 amp circuit breaker, but #12 copper wires connected to a double pole 20 amp circuit breaker would be better choice.

If the compressor is cord connected (or even directly wired) with the minimum sized wires, it will likely a voltage drop problem unless very close to the panel. This problem is more pronounced as the distance between the circuit breaker and motor increases, or when smaller wires are in the circuit. All the voltage at the circuit breaker does not reach the motor, as it is lost as heat; so the compressor only sees 90 to 105 volts instead of the 115 volts it expects.

If the cords, connections, etc are getting hot, it is a tell tale sign of under-sized wires and /or poor connections. Once you solve these problems, the compressor should run "as advertised " because motors usually don't "go bad" but fail all at once. Unless you have a bearing problem - or there is a problem with the load itself (compressor).

I hope this helped.

I would think that compressor would cost a lot of money.So if I were you I would buy a new refrigerator .

Pump speed Selector Switch Contact Probably Missing, Checkout

this could be blow back possibly bad piston rings you may need new rings oil chamber is usually at intake pressure unit may need rebuild

I worked for a tool rental company while attending college and learned a great deal about engine /compressor combinations. AOSmith compressors used mainly ford engines to power their reed valve compressor head. The mechanic would use off the shelf carbs from local auto parts store. I would recommend that you remove the carb looking for an id tag or numbers stamped on the carb body to cross refrence it for rebuild kit or just exchange. The carb will not be for a 460 engine however. Since 1/2 of the engine is used for pumping air, the carb will be for an engine of lower displacement. We also rented a brand called Lindsay that used a Chrysler eight cylinder engine with their own design of reed valve head. These compressors would work pretty well untill the reeds started leaking, causing the engine to labor. Easy test, with engine off apply compressed air to discharge port (100psi), with cover removed from compressor head, listen for air escaping past reeds. Repair as needed.

If the motor is running, if the motor shaft is turning and is connected properly to the compressor piston assembly, if the piston seals are not worn to the point that the air is blowing by them, and if the intake valve is working properly, then you should be compressing air.

There will be an air intake filter near the top of your compressor head. Take the filter off and run the compressor. Air should be being sucked into that small opening, and no air should be coming back out. Is there?

If there is, it would suggest that the intake valve has failed, and now all your compressor is doing is pulling air into the cylinder on the piston retract, and then blowing that same air back out the intake hole on the compression stroke.

Air flows to the path of least resistance, and if the intake valve has failed, the path of least resistance will be right back out the same hole the air came in through.

For more answers to related problems if this is not the case for yours go here............
http://www.about-air-compressors.com/compressor-will-not-build-pressure.html

look for the line out of the compressor,if there isnt one start the compressor and start connecting the piping from there,go about a foot from the compressors output then install the gauge inline,then the air shutoff,then the hose,the reason being a foot from the compressor is the heat from the compressor running wont damage the air gauge

There may be a wiring diagram either on the body of the motor or inside the wiring terminal cover.
A.O. Smith can be contacted at 800-262-6484. If you do call, have pertinent motor info ready.