Harbor Freight Compresser

Bick

Keilau,

The only way to adjust pressure with the 1/5th HP HF compressor is to adjust the bleed valve on the bottom of the moisture trap while spraying. If the bleed valve is closed, the compressor will cycle on/off as you describe but at a pressure that varies from 42 to 55 PSI which is much to high for most model AB work (there is a significant drop in pressure as you spray with the bleed valve closed but not low enough and there is a 'blast' of air as you first depress the AB trigger). If you adjust the bleed valve so the spraying pressure is ~20PSI the  compressor WILL run continuously as air is diverted through the bleed valve. Unfortunately the manual doesn't describe adjusting pressure but simply (in the parts listing) describe part 23 as a "valve screw". There's likely nothing wrong with B-17 Guy's pressure switch or compressor. Indeed, one of the Iwata compressors has a bleed regulator and it, too, runs continuously.

Bick,

You are absolutely right about your assessment of the HF compressor and its bleed air regulator. I thought of that after I posted.

Unfortunately, there is no airbrush that operates at about 42 psi. The design is faulted. No option is going to be cheap for B-17 Guy. He can try to replace of the regulator with a true diaphram type regulator/filter unit and hope that the auto on-off switch works.

The HF compressor manual stated a 500 hours operation life, but it is possible that some units can work longer than that. B-17 Guy can use his as is until it dies a few years later.

Keilau,

The only way to adjust pressure with the 1/5th HP HF compressor is to adjust the bleed valve on the bottom of the moisture trap while spraying. If the bleed valve is closed, the compressor will cycle on/off as you describe but at a pressure that varies from 42 to 55 PSI which is much to high for most model AB work (there is a significant drop in pressure as you spray with the bleed valve closed but not low enough and there is a 'blast' of air as you first depress the AB trigger). If you adjust the bleed valve so the spraying pressure is ~20PSI the  compressor WILL run continuously as air is diverted through the bleed valve. Unfortunately the manual doesn't describe adjusting pressure but simply (in the parts listing) describe part 23 as a "valve screw". There's likely nothing wrong with B-17 Guy's pressure switch or compressor. Indeed, one of the Iwata compressors has a bleed regulator and it, too, runs continuously.

B-17 Guy

I have the one in the pic above. Mine runs constantly once I turn it on, is it not supposed to? It works for me very well, I havent had to complain yet. Seriously though, is it not supposed to run all the time?

The answer is in page 9 of your user's manual, #5. And it is "no", the compressor motor is NOT supposed to run constantly. After you turn on the power switch, the motor will run a few seconds and then stop. The motor starts whenever you push the airbrush trigger to spray and stops again when you stop the airbrush.

This automatic pressure switch (Parts #31) was designed to reduce wear and tear of the compressor. When the motor runs, the friction generates heat that wears down the lubricating coating on the piston and cylinder wall. (It is an oilless compressor.) So you don't want it to continue to run when not using the airbrush. On the other hand, it will work if the motor runs continuously.

If you airbrush for 30 minutes, how hot your compressor gets? The HF compressor will probably get too hot to keep your hand on the compressor if the motor runs continuously. You should have the pressure switch repaired or replaced. 

I have the one in the pic above. Mine runs constantly once I turn it on, is it not supposed to? It works for me very well, I havent had to complain yet. Seriously though, is it not supposed to run all the time?

I made a mistake in my other post , I have the 1/8 hp unit. I just took it back and now have another one. Hopfully this is a good one.

Bill

fermis

I too have the same unit. It would shut off at 60psi. Once below 55 or so, it'd kick on. Within a month or so, after kicking back on 4-5 times, pressure would go down to near 0, before it would kick back on. I just adjusted the valve at the bottom, so I get a constant 30psi, and just let the thing run. One "on", one "off" per session is a lot less wear and tear.

If the compressor motor runs continuously on, it gets a lot MORE wear and tear. If the auto-on-off switch does maintain a constant pressure and turns on the motor only when air flows, the compressor is defective.

I too have the same unit. It would shut off at 60psi. Once below 55 or so, it'd kick on. Within a month or so, after kicking back on 4-5 times, pressure would go down to near 0, before it would kick back on. I just adjusted the valve at the bottom, so I get a constant 30psi, and just let the thing run. One "on", one "off" per session is a lot less wear and tear.

wjbwjb29

It is the 1/5 hp compresser and by 90 minutes I meant without any air leakes it shouldnt come on at all sitting idle. This is a best guess estimate it may have been longer but it was good. I sprayed all the conections with sopey water an was happy to find no leakes [last week] but this week it went crazy.

Bill

Is this the compressor you got? Notice that the regulator has no adjustment knob on top. It bleeds air out through the bottom of the regulator when set at low or zero pressure. It will guarantee the motor turns itself on continuously at low pressure setting. What happens when you set pressure at, say, 20 psi with an airbrush?

Bill,

If you have the 1/5th HP one (usually comes with an AB), you likely have a 'bleed' regulator. Check the air pressure screw adjustment on the bottom of the moisture trap and make sure it's tight.  The 1/5 HP HF normally runs continually unless that valve is closed (you adjust pressure by 'bleeding' air through it). Since you don't find leaks elsewhere and since it does cycle, sounds to me the pressure switch is working. Also make sure the moisture trap bowl is screwed in tight. FWIW

It is the 1/5 hp compresser and by 90 minutes I meant without any air leakes it shouldnt come on at all sitting idle. This is a best guess estimate it may have been longer but it was good. I sprayed all the conections with sopey water an was happy to find no leakes [last week] but this week it went crazy.

Bill

wjbwjb29

Hello;

Well I guess I have a bad compresser. I was thrilled with the silence. Last week I got it all conected and was checking all the fittings for leaks and there were none, took maybe 90 minutes for it to run when sitting idle. Today I cant get the thing to stop running. I look at the guage on the compresser when it gets to its pressure and it looks like a stopwatch ticking off the seconds. OK guys tell me if my thinking is right, I dissconected from eveything, so I have just the unit and hose and I turned the regulater to zero pressure, in another words no air is required, so the uinit should not run right ,but in goes on and off rather quickly. I have only had the compresser 2 weeks. At first I thought it was a bad hose that is suppleyed with the thing.  any thoughts

Bill

It does not sound normal. The HF has a 90-days warranty. I will return it or exchange as soon as possible.

What compressor did you get? What do you mean by "took maybe 90 minutes for it to run when sitting idle"?

Just guessing, but sounds like a bad cutoff switch. When it gets to a certain pressure the cutoff switch engages and does not allow it to start again till below a certain presure. If it goes out it can do as you have described. If it's still under warrenty, take it back if from a store or find out about getting a replacment.