Dewalt compressor not filling with air

probably part # 30 here

http://www.ereplacementparts.com/dewalt-d55155-type-compressor-parts-c-1009_3079_3080.html
Dewalt D55155 Type 1 Compressor Parts

The issue of low pressure that you experience is usually caused by air leaking from various fittings and or broken valves or valve plate gaskets. While the compressor is filling, spray soapy water on all fittings checking for leaks. If no leaks are found then suspect the head area of the pump. Usually when valves are bad , you will notice that air is blowing out of the intake port. With air filter removed and tank empty of air, start compressor and feel for good suction at intake, as the compressor reaches maximum pressure, air will begin to blow out of the intake and you will not feel suction. If this is the case, replace valves and or valve plate gaskets. ;good luck with ;your repair.

cool

Compressors draw alot of amps.maybe your braker isnt big enough. clean the air intake filter.

The cold start valve will close when volume of air from compressor is sufficient to overcome spring under pin (allows the motor to come up to speed). Evidently your compressor is producing very little air. Usually the problem is leaking or broken reed valves or gaskets. Remove the head and look for torn/ leaking gaskets and replace as needed. Examing the reed valves and seats and look for broken cracked reeds or worn seats. Some of the valve plates used in Dewalt compressors are made of aluminum and would fail. Parts are available at www.toolpartsdirect.com or local dewalt service center. Good luck with your repair.

Maybe a pressure valve.

Can you hear the air coming out? Or it is not pumping up at all? If the air is not coming out somewhere like the bypass or the regulator, or the drain plugs, then the reeds are shot in the head, it is an easy fix, and an easy part to get, I hope, call Dewalt's hotline and tell them what's happening, they will fix you up.

The bleed valve is an unloader of sorts that allows the compressor to start with-out a load. It closes when the pressure in the airline reaches about 20-25lbs with good volume. If air volume is not sufficient, the valve will not close. To solve the problem lets do a few tests. A long cord will reduce power and reduce air volume. Try powering the compressor with-out extension cord. If bleed valve closes when you do not use a cord, the compressor is not getting enough voltage, use shorter cord of the 12 gauge quality and more hose to reach work. If valve still does not close, check for air leaks on all fittings including around pressure switch and drain valve with soapy water. Repair as necessary and retest. If no leaks were found, temporarily plug bleed valve port with screw/bolt and run compressor till set pressure cut-off while counting minuites/seconds. The compressor should fill and shut off within three minutes or so. If it takes an unusually long time to fill, then the reed valves /valve plate is worn and leaking pressure back into cylinger. Leaking valves will usually result in very hot discharge airline/air. Reinstall the bleed valve after test. Parts and partslist are available at www.toolpartsdirect.com . Good luck on the repair and email if you have other questions.

Some dewalt air compressors with single cylinder are known to develop trouble with reed valves and /or failed gaskets in head. Parts lists and parts are available at WWW.toolpartsdirect.com Simple test is to remove air filter and check for suction at intake. Bad reeds will tend to blow air out intake as pressure increases. Failed gaskets in head will cause very high temp at discharge hose. Parts are not too expensive. Enjoy

hi your problem seems to lie with the valves in the cylinder head not sealing i suggest you obtain a new valve set and replace said items
hope this helps