3gal. aircompressor - craftsman model #921153101

I have worked on compressors from 15 PSI all the way up to 5000 PSI and everyone of the regulators I have seen bleed the pressure of when you dial it down and you can hear it.

Is the petcock down below open or closed? If open, then screw it closed. Also, is the compressor portion connected to the motor working as it should? As the motor reciprocates, it should operate the compressor piston that pumps air pressure into the tank. Maybe something is broken there.

It sounds like a bad gasket. Either the one between the valve plates or the one between the head and top valve plate. The top gasket is the most common one that fails. If the middle of the gasket is broken, where it separates the intake from the exhaust, you will get symptoms just as you described. Will only build up a small amount of pressure. Here is a link to look at the parts diagram and to order parts from.

http://www.searspartsdirect.com/partsdirect/part-model/Craftsman-Parts/Air-compressor-Parts/Model-921153101/0247/0703000/50037535/00001?blt=06&prst=&shdMod=

Air compressors generally use a check valve at the tank to prevent loading of the compressor at start of cycle. Easy to check. With unit powered off and pressure in tank remove fitting from compressor to tank and test for leak. Check valve is uaually brass or steel and can be removed and sometimes cleaned. If faulty, replace with generic valve available thru WWW.grainger.com. If you find that your airline from pump to tank is full of carbon deposits, you will most likely need to clean airline and decarbon headvalve area. Even is tank checkvalve is leaking, valves at head should hold pressure. Since your pumps leaks thru intake indicates valves are not holding pressure. Good luck with your prepair.

The evolv air compressor was primarily designed to power a very small nailer. The pressure regulator (knob in front) should be turned clockwise till it stops to attain full pressure. At this setting it should air your tire. If not you may have a defective regulator. There is a trick to get full pressure from your tank. Notice the small pressure safety valve on the side of the unit. You could remove this valve and install a fitting giving you two ports. One for the safety and other for a quick disconnect. This second port will give you access to tank pressure without going thru the pressure regulator. This mod is safe because you still have access to regulated pressure when you need it. Good luck

The image below is an exploded view of the motor on the 3gal 1.5hp craftsman compressor. There are no belts for this model.
For more info check out the link I provided

http://www.mastertoolrepair.com


hope this helps.

sounds like a valve broke and you need to replace the valve plate.


http://www.mastertoolrepair.com/sears-craftsman-921153101-p-24902.html?osCsid=ke90vvsu0rof263nthcsf9e9a1

I had same problem, i ended up reverse bleeding it with airline at work. Regulated pressure down to about 5 psi, then attached hose prefilled with brake fluid between bleed nipple and airline trigger and gently sqeezed trigger till fluid came out in resevoir.Helps that i work in a hose distributor and have all the hose and fitting to hand mind. hope this helps

your pressure adjust valve is stickn unless your bottom valve isnt shut all the way

The needle valve that you see is the unloader which releases air pressure from the discharge line after set pressure is obtained. If air continues to leak after the compressor shuts off, the check valve installed in the tank is leaking air out of the tank. Follow the air discharge line from the compressor to the tank. There you will find a brass valve which is the check valve. Simple test is to remove the smaller airline (1/4") from the brass valve and check for air leaking. If leaking remove brass valve and check for debris under the white seat. If you cannot clean the valve, replace with generic check valve from www.grainger.com. It will cost less than factory part. Just order the valve considering the fitting sizes that you need. For exact replacement,( www.sears.com parts). If you sears model # begins with WL then your compressor is made by campbell hausfeld and parts may be ordered from www.chpower.com. Good Luck with you repair and email if you have more questions.