Regulator issues on Central Pneumatic air compressors

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by James
(Charleston,SC 29406)

i have a central pneumatic by harbor tools i had 2 years. I didn’t know regulator was not working until my friend blew his boat tire up…i probably bought it broke and didn’t know it . It is now discontinued and no PARTS available.

It is a 2 HP 8 Gal tank, 2 gauges one big i guess tank cause it cuts off when full, and a smaller one adjustable too. Says 140psi and tank says max 114 psi can’t seem to find the part can you help?


Central Pneumatic 2 HP 8 Gallon air compressor
Central Pneumatic 2 HP 8 Gallon air compressor

As you say, your compressor will have two gauges.

One is the tank gauge, which displays the pressure level of the air in the tank. It has nothing to do with turning the air compressor on and off. That function is provided by the pressure switch.

The second gauge, the one closest to the discharge coupling to which you connect your air line, is the regulator gauge. It displays the pressure setting on the regulator, and the pressure that the air tools will get from the compressor tank, as long as 1) the regulator pressure is set equal to or LOWER than the tank pressure and 2) the air tool uses less air to run than can be built by the compressor.

If you turn the knob on the regulator, that gauge reading should change. If it doesn’t, it might be a failed gauge, or a failed regulator.

The regulator will be a common, general purpose one, and you will (should) be able to find a replacement at any shop that sells air compressor parts unless it’s part of a manifold. The it may be more difficult, and expensive, to replace.

Pull the plug, dump all the air, and remove the existing regulator. Take it with you to the store so you can get one with the same ports sizes and regulator size.

Pressure regulator knob for model 94355

by franklin davis
(chattanooga ,tn usa)

where do i find a pressure regulator knob for this model #94355 air compressor
Franklin, the logical first place is Harbor Freight, the folks that own the Central Pneumatic brand.

Failing that, visit any store that sells air compressors and they will normally also sell general purpose air regulators for those air compressors.

Since general purpose air regulators are pretty much all the same, as long as you get one that fits, you`re good.

Note that I didn`t say buy a knob. For the DIY home air compressor owner, finding parts for any of the compressor accessories is nigh unto impossible, and they just are not stocked in most stores. You probably will have to buy a new regulators.

Update to Ray – Pa. (Central Pneumatic 3H.P. 3 Gal. #90385)

by Ray

#90385 Parts List
#90385 Parts List
#90385 Parts Schematic
#90385 Parts Schematic

Update to Ray – Pa. (Central Pneumatic 3H.P. 3 Gal. #90385) After some reading on your site I did some further checking on the compressor.

Air intake at the filter is good!

And if hole in the oil plug is sealed, the compressor will fill tank, and cycle like it should.

The terms used for parts in most of the articles don’t match up with parts listed in the assembly drawing for #90385. (I’ll try to send a copy of the assembly drawing.)

Could it be the cylinder down washer that’s the likely problem?
Ray, I cannot connect this post to your original post on this site. I tried, sorry. There are just too many posts for me to be able to do so.

If, in reading this post, your complaint is that air is blowing out the oil vent hole, then that is an indication of piston seals allowing air to blow by and into the oil sump instead of into the tank.

A failing pressure valve in the pump head, as might a plugged up tank check valve, could be forcing an increasing back pressure situation which could increase the pressure on the piston seals.

I am sorry, by the time I blow up your parts list and parts schematic for the CP 90385 compressor, I can’t read what it says. Old eyes, I guess.

Anyone else with a Central Pneumatic 90385 compressor with the same problems is sure invited to add a comment.

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Central Pneumatic 3 gallon pancake compressor. Tank pressure tops out at 100 psi. Tool pressure regulator is set to 80 psi to operate a nail gun for 2″ fence picket nails. Once a couple of nails are driven, the tool pressure regulator gauge drops too low to operate the tool, but the tank still has plenty of pressure. Shouldn’t either the tank boost the pressure on the regulator gauge back up to 80 or shouldn’t the compressor turn on? This isn’t happening.