Question about Craftsman Air Tools & Compressors

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I have a craftsman air compressor model # 921.16472S. When it got to cut off pressure the bleed valve started blowing. I changed the pressure switch and bleed valve then lowered the cut off pressure. When it got back to cut off pressure the bleed valve blew again. What could be wrong with it

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  • 37 Answers

Either the pressure switch is not shutting off when reaching the desired pressure or the pop off is either the wrong one or it is bad. Some blow off at lower pressures for single stage air compressors while others blow off higher for 2 stage air compressors.

Posted on Feb 20, 2014

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Posted on Jan 02, 2017

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SOURCE: air compressor problem

Cheap oil-less compressor, normal.
If you don't like it, buy one that uses oil and a drive belt.

Posted on Oct 07, 2008

  • 19 Answers

SOURCE: Air leakage through pressure switch needle

1)Let your unit pump up.
2)Turn it off.
3)Find the supply line from the pump to the tank.
4)Remove the supply line from the pump head.
5a)If you hear air coming from the tank you have a bad check valve.
5b)If you do not hear air coming from the tank, you have a leaky
pressure switch.

Posted on Feb 02, 2009

  • 68 Answers

SOURCE: Craftsman 3.5 hp portable air compressor keeps blowin head gasket

I would say the head or block is warped. Use Majic Marker to cover the mating surfaces , the head can be rubbed on a flat surface like a cast iron table saw to find the high spots, or the head can be rubbed on the block.
Careful work with a good flat file will remove the high spots.
The torque value sounds low even for an aluminum block, you could check with a small engine shop to get their opinion.

Posted on Apr 25, 2009

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I have a Craftsman (919.176820) 2HP, 12 gal. compressor. I starts fine the first time, it reaches full pressure and cuts off. When the pressure drops and it tries to start again, the motor lugs and trips...


Your tank check valve is stuck/broke. It's on the tank end of the line from the pump to the tank. It is supposed to close when the pump stops to keep air in the tank and let the system bleed pressure out of the pump so the motor can start when there is pressure in the tank. The part you need is CAC-437-2 and is available through searspartsdirect.com.

Feb 22, 2012 | Craftsman 33 gal Air Compressor 6 hp...

1 Answer

Craftsman 5 HP MO-6436 Unit will run, pressurize, and hold pressure pretty good. But, after use has decreased pressure to the cut-off point where it should kick back on, it does not. Well, it turns...


If the unit does not unload properly the motor will have difficulty starting. Make sure that the intank check valve is not leaking air back out of tank (with pressure in tank, remove hose from compressor at tank checkvalve and spray soapy water). Replace as needed if leaking or try to repair. If the valve is not leaking then issue my be unloader valve at the pressure switch. Follow small airline from checkvalve to pressure switch. Small valve stem at the pressure switch should release air in line when pressure switch cuts off. Listen for small amount of air to be released when unit shuts off, if air continues to leak out, then check valve is leaking. Replace with generic parts making sure of fitting size. Good luck

Mar 08, 2011 | Craftsman Air Tools & Compressors

3 Answers

Compressor runs to 175psi but trips pressure relief when pressure drops tries to restart motor but motor wont turn blows breaker. changed whole pressure switch have same problem.


The problem is lilkely the check valve between the compressor and the tank -- it is alowing pressure to build from tank to compressor preventing the compressor from turning over. Clean, maybe replace, check valve...

Charlie

Jan 09, 2011 | Craftsman 25 gal Air Compressor 3 12 hp...

1 Answer

Craftsman 1 HP 8 gal vertical compressor.919


Sounds like the unloader valve is not working properly. The unloader typically is at the end of a tube going to the pressure switch. The unloader is tripped when the pressure switch cuts off. The purpose of the unloader is to bleed the pressure from the cylinder when the compressor cuts off so the next time the compressor cuts on it will be starting in an unloaded condition.
when the compressor cuts off you should hear a discharge of air for about 3 to 5 seconds if the switch is working properly. The unloader can be adjusted if necessary by loosening the jam nuts and adjusting the unloader towards the lever on the pressure switch.

Apr 05, 2010 | Air Tools & Compressors

1 Answer

Craftsman Pancake Compressor loosing air while compressor is running. I tore it apart and there is a bolt with a pin sizes hole in it in the side of a brass fitting. What is this fitting for. It only...


That is likely the compression release. A pintle valve in it should close while the pressure switch runs the compressor. After the switch cuts off, the valve is released to bleed the pressure off the cylinder head of the compressor to allow it to restart without having a load on it.

When the pressure switch cuts off you should hear a woosh as it bleeds but it should NOT bleed while it is running. Take it apart and clean the seat. Be careful of springs that go sproing.

Mar 10, 2010 | Craftsman Air Tools & Compressors

1 Answer

Compressor motor only comes on and fills tank when tank is empty. When tank has any pressure it tries to start but stops.


there is a valve under the regulator, at switch off pressure the valve must blow of the air between cilinder and checkvalve after stop running.. when checkvalve is not closed it keeps blowing.

Feb 05, 2010 | Craftsman 3 gal. Air Compressor, 1.5 hp,...

1 Answer

Craftsman compressor model no 919.153160 Runs fine, but does not build up pressure past 60PSI. Will not shut off as the pressure does not reach to cut off pressure. Where to start looking>


you have a valve problem in head /or leaking head gasket /or a bad leak in system
take off breather and see if it is pulling air it sould not be pushing back
one other thing would be the unloader at pressure switch or tank check valve

Dec 30, 2009 | Craftsman Air Tools & Compressors

1 Answer

When my compressor cuts out, it starts losing air by the auto pressure control (LEFOO LF10). I removed the plastic cover and felt the air coming out a little valve.


The air is probably coming through the unloader on the pressure switch. This is designed to vent the pressure between the compressor pump and the tank so that the compressor starts easier. This venting should only take a few seconds (5 to 10). If it bleeds air continuously, until the compressor restarts, then the tank check valve is bad. This is usually a fitting that extends into the tank. The small tube to the unloader usually goes directly from the pressure control switch to the tank check. Depressurize the tank, remove the check valve, and try to clean it. If that doesn't work, replace it.

Dec 29, 2009 | Craftsman 3 gal. Air Compressor, 1.5 hp,...

1 Answer

Compressor fly wheel not hung up unit starts operation soon fly wheel starts to slow down like it is laboring then stops and motor overloads and trips protection switch


It sounds like the unloader valve it not working correctly. The unloader valve bleeds off the pressure between the pump head and the tank check valve. Without it every time the compressor starts the piston would be working against the max tank pressure. This would cause what your describing. However when the unloader valve is not working the pump will shut off with in a couple seconds. If your pump is working longer then that I would guess that the unloader valve may be bleeding off some but not all the pressure.

On most smaller craftsman compressors the unloader valve is comprised of a piece of tubing running from the cylinder head or the check valve to the switch. At the switch you will see a plastic tip with a pin running to a small trip lever. Make sure that it's moving freely and moving through it's full range of motion. It's impossible to describe how this looks and feels to someone who has never messed with one of these.
After you have checked it and made sure it's working, if you still has trouble after this please let me know.

Oct 15, 2009 | Craftsman 3 gal. Air Compressor, 1.5 hp,...

1 Answer

Air Compressor shuts off


Most compressors have a check valve installed in the tank that allows air from the compressor to enter the tank and not allow back pressure to the compressor. Also there is an unloader valve at the pressure switch that activates when the pressure switch cuts out releasing the pressure in the line. These two devices allow the compressor to start in an unloaded condition so that the motor will not strain. When you place you finger on the intake, the compressor is no longer pumping air thus there is not load on the motor. Your problem may be the intank check valve or the capacitor may be weak or bad. Simple check for both. Many volt meters have capacitor check and amp draw. The capacitor should not be more than 10 percent or rating. enjoy

Nov 28, 2008 | Craftsman Air Tools & Compressors

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