AS189 – Is My Compressor Faulty?

Some of you guys may remember that a fairly long time ago I published an air compressor review and at that time I could not predict that it would be probably the only compressor review on my website (at least for now).

I believe that it has helped a lot of people to make the choice. I feel a bit ashamed that I could not provide more reviews because there is many thing going on in my life right now. As you know I have not written anything for almost two months.

But recently I got an email into my in-box and after replying a few times I have realized that I haven’t made myself clear when I wrote that compressor review down.

I’m not going to post the whole conversation here but I’ll try to explain the whole situation from both sides in shorter form.


I’ve recently bought the as189 compressor. I would like to ask, when the regulator is set to max i.e. 6 bar and when the airbrush is depressed for a prolong time, should the pressure drop on the regulator manometer? Because when I depress the airbrush the pressure drops down all the way to about 2 bar. Due to the limited time for exchange I’d really appreciate your insight. If my compressor faulty?

My airbrush is using the 0.3mm nozzle right now, here is more info :

Model EAD-K431
Feed Type Gravity & Suction
Nozzle Size 0.20 & 0.30 & 0.5 MM
Needle Size 0.20 & 0.30 & 0.5 MM
Cup Capacity 7 & 22 CC
Working Pressure 15-50 PSI
Air Hose 1.8 M (G1/8 Female connections)
Adaptor G1/4 Female to G1/8 Male

And the compressor is the AS189, off course :

Air flow 20-23 L/min
Auto start pressure 43 PSI (3 BAR)
Auto stop pressure 57 PSI (4BAR)
Max Pressure 57 PSI (4BAR)
Air Tank Size 3.0 L
Power 1/6 HP

The trigger on the airbrush is depressed and held depressed, air expels through the airbrush. The pressure on the manometer drops all the way to 2 bar and maintains there. Is it normal?

You said about setting the working pressure, how to set it with the compressor and airbrush that I have.

When you do the AS189 compressor review, in the first video why is it your pressure is only at about 2 bar and not up to full 6 bar?

So at first I didn’t got that the pressure drop wasn’t sudden but took a little while, so I recommended this:

Check for air leaks. It may be, for example, O-rings in your airbrush can’t handle 6 bar pressure and it’s leaking somewhere inside.

Or it might be a loose connection on the hose.

But if you find any air leaks around manometer or regulator then it is compressor fault and you may want to return it. The leak could be well hidden that you can’t even hear anything then it takes even half a day to loose that pressure.

For example I started to notice that even if I finish working with my compressor and the tank is full, next day it’s empty. It doesn’t bother me that much because it holds the pressure when I need it and looses it only in a long time period which is fine with me.

Also if you push the trigger on your airbrush it shouldn’t drop that much unless you have some big spraying gun with big nozzle size.

When you setting up the working pressure, you should have full tank with max pressure of 6 bar and then when you open the air channel of your airbrush the pressure will drop in a seconds but let’s say to something like 5 bars (not 2), then when the airbrush is still depressed you use your regulator to set your working pressure to something like 2 bar. The point is to find optimal pressure for your work and minimal changes on the manometer.

All the time when compressor is on it is pumping the air into tank up to 6 bar and then it will shut off but as soon as you start spraying it will drop to preset pressure of 2 bars.

He ensured me that there are no leaks when fully connected, with the valve on top of the regulator turned to ‘+’ fully. Compressor turned on and pressure builds up and the manometer shows 6 bar.

The I got the video of actions he took so that I would have better look on the situation.

To control regulator you have to pull the valve up, only then it will have effect (just see video).

[responsive_youtube wut4IHMPmCs]

At the start, the compressor was already running for at least 2 minutes. The regulator is at the “off” position which is the ‘‘ side.

As you can see at 0:32min I turned the regulator to the ‘+‘ all the way to full and the manometer shows the pressure going up to 6 bar.

At 01:20min I depress the airbrush trigger. As you can see the pressure drops to 2 bar and remains there.

At 03.37min I release the trigger and the pressure slowly builds up. When depress again it drops to 2bar and stays there.

After watching the video my answer was:

Your compressor is perfectly fine ;)

I had 2 bar (not 6) because I have already set the working pressure up to 2 bar for the airbrush. You also don’t need to have it at 6 bar. You set it to 5 or 6 bar when you use bigger nozzle in airbrush. For painting art and detailed work just regulate it to 2 bar and you gonna be fine.

Do it while depressing airbrush in short periods.

When you set it up it means that it will release less air while you airbrush and it will last longer because the pressure in tank will still be 6 bar no matter what you set on regulator.

On your video everything looks fine, compressor is OK, so don’t worry.

I misunderstood you that the pressure drop is sudden, like in couple of seconds.

That’s all about explaining the function but here one more tip.

Because the tank is small, it gets empty very soon, it means the compressor has to work more, so from time to time give it a break to cool down.

Also when you overheat it you are not just risking to burn it out but the heat creates water condensate inside the tank so don’t get scared when it spits water. Just use some additional moisture trap.

Guys, if you have anything to add just leave a comment, I and all my readers will be thankful.


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