# An annoying compressor



## JackM (Jul 29, 2008)

I have one of those oilless pancake compressors from Harbor Freight (pretty much identical to other sources). I keep it in my basement and use it for my air brush in winter and to power my pneumatic turnouts in summer. It has an annoying habit: every thirty seconds or so, it runs for about five seconds, whether or not it was used.

I've done the old soapy water test a dozen times to every conceivable part but I can't find any leak, whether air bursh or switches. Both gauges indicate it fills to the max. 100 psi, then drops 2-3 psi, and instantly feels the need to refill back to max. (I have a bigger compressor in the garage and it doesn't do that.)

There's a warning label that indicates I shouldn't try to adjust it, but I've taken the housing off and I don't see anything adjustable anyway. It's really not much more than a nuisance, and a waste of electricity. Since it's in the basement, it's not audible outside so not noticeable when running the trains. But it's really annoying when I'm using it with my air brush.

Anyone know if there's any way to adjust it to not be so sensitive?

JackM


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## Michael Glavin (Jan 2, 2009)

Jack, 

Most air compressor switches are adjustable for pressure cut-off verses pressure cut-in. Your description is sounds like the cut-in differential is too close to the cut-off and or pre-set cut out pressure. I don’t think you can hurt anything trying to adjust the pressure switch; on the other hand it’s more likely than not your switch has a fixed cut-in differential so it’s not adjustable. A replacement switch is likely in order. 

Grainger’s has air pressure control switches of varying specifications, simply review the specifications for a replacement choice or I can help if you like. 

Also make sure the compressor is NOT full of water, compressors compress air and a byproduct is condensation of the moisture in the air it consumes, the water condenses within the pressure vessel. I have seen many an air compressor full of water… 

Michael


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## John J (Dec 29, 2007)

I have seen the water in the tank problem. I have seen 40 Gal Tanks half or more full of water. It reduces the volume of the tank drastically. With the water in the tank the compressor can fill the void quickly. On the other hand when air is used the volume of air is consumed quickly. I think it is water in the tank. 

JJ


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## Totalwrecker (Feb 26, 2009)

Might be water, but I think it's the difference between HF and spending a few $ more at home despot. My little twin tanked Stanley, similar in size to yours, has a working range of 30 pounds before it cycles back on. Your regulator isn't right. 
I think of HF as a 'throw away' tool store, if a tool last longer than the job it was bought to do, it's a bonus! 
My Stanley has been rained on and baked in triple digit sunshine, there's a roof over the deck, just no walls. Unless railings count. Bought on sale.... Sometimes a brand name makes a difference ... and.... Chicago Electric isn't one.... 
Harbor Freight can afford to keep handing out replacements until you get a good one, while Stanley will get it right the first time. Any known brand, Stanley was on sale when I was shopping. 
I do use HF pin nailers and replace 'em as I wear 'em out, but any tool I want to last and I'll spend for the quality, if it's on sale! 

Happy Rails 
John


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## JackM (Jul 29, 2008)

The water idea sounded reasonable since the compressor's in the basement, turned on/off with a good ol' X-10 so I haven't opened the drain in a while. So I checked it and...no water at all! 

So that brings me to the pressure switch, which is what I've been thinking, except that I don't see no stinkin' pressure switch. Seems like there's only the two guages. My copy of the owner's manual has disappeared so I'll have to go onlnine later and see what I'm missing. 

JackM


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## gtrainman (Jan 5, 2008)

Air compressors have a in-line check valve somewhere in between the compressor pump and the tank. (it may even be built into the compressors air pump). Your compressor is kicking on because of pressure loss in the tank. Even if you do have an adjustment for the drop in pressure for it to kick on and refill, it still will continue to kick on as air drops pressure just with more than a few pounds of air drop. To me, it sounds like air is bleeding back through the pump cylinders and or pump valves somewhere causing the air pressure to drop in the tank due to a leaky check valve.


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## JackM (Jul 29, 2008)

Took a look at the compressor's manual online. It's supposed to pump up to 100 psi then shut off and not start pumping until pressure drops to 85 psi. Mine drops all the way to 97 psi (!) and then starts pumping again. The friendly parts order guy on the other side of the planet (pretty good, actually) told me that a replacement pressure switch is not available. No use in any hand wringing over this. With its near-constant pumping, how long can it last? I'll be buying a replacement compressor soon enough. 

If there's any one product I hafta say HF is lousy for, it's their compressors. I have a bigger one in my garage; the first iteration of that unit was replaced after a few months - it was winter and wouldn't start on cold days. The emergency stop button hasn't worked for a year or two and I'm waiting now for a little six-inch hose that's on backorder. A few years back, I was visiting my brother in Phoenix when he had to replace his big honkin' stand-up unit at his local HF. I never spring for the extended warranty for anything, but HF compressors might be the exception to the rule. Or buy somewhere else. 

But the thing I have to say in their favor - I've learned a lot about tools that I never knew existed. Planisher. English plane. Wobble extension. As someone said, if it's something you'll only use once or twice, their stuff is probably good enough. You don't often see real tradesmen there. 

On the other hand, sometimes "professional grade" isn't right for an amateur like me. Like that "pro" string trimmer I bought when I got this place. My garage's rear door needs some siding work to fix the little chunks of vinyl siding I chipped off with it. Couldn't control the damn thing. Two trimmers later, I have a nice, sedate Black & Decker. It can't even hurt my ankle. Guess how I know. 

JackM


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## East Broad Top (Dec 29, 2007)

A few things. (I've got a similar Porter-Cable pancake compressor) If I leave the hose connected to it, it will slowly leak air over time, prompting the compressor to kick in. So I always just pull the hose off once I'm done so not to lose pressure. I also turn the switch off when I'm not using it, so it doesn't unexpectedly kick in at odd hours. The air stays in the tank, so I've got plenty for quick tire-filling jobs without having to wait for pressure to build up. Don't know how helpful this is to your issues, but I can understand the frustration. I can almost not stand to be in the garage with my compressor when it's on. Next one will be much quieter. 

Later, 

K


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