Harbor Freight $99 compressor Problems

[tom]

Use more hose, less extension cord. Tom

[Jeff Wisnia]

Sound like it doesn't have an "unloader valve" on the compressor to relieve it of having to work against pressure in the tank when it's trying to start. That's why it will restart when you drain it down to zero gage pressure, but not when you are just down to the "start" pressure.

What do you mean by "heavy duty" extension cord? What gage wire does it have in it? And how long is it? There is no theoretical reason why you can't make an extension cord of even several hundred feet length that would support the starting load. But there are practical reasons like weight and flexibility. If your extension cord is made with less than No. 12 gage wire, get a heavier one.

BTW, that 2.5 HP rating is a BS "peak horsepower" number, just before the motor stalls out and burns up. You can't get a 2.5 HP motor to run continuously off a "normal" 115 volt circuit.

You get what you pay for. A better and more expensive compressor will have an unloader system to prevent just what you are experiencing.

Google up "unloader valve" and see what you can buy to add to your compressor.

HTH,

Jeff

[Duane Bozarth]

Then the cord isn't heavy . If it can start on the wall circuit but not on a cord, then you have excessive voltage drop. Case closed.

[Pop]

: > The compressor(Item No. 90385-4VGA) works fine when plugged into a : > 115v outlet, but not when connected with an extension cord. Even a : > heavy duty cord causes the push-button circuit breaker to blow when it : > trys to restart after the pressure falls and the unit tries to kick : > in. When you push the button, the unit tries to start but kicks the : > breaker after about 1 second. Sometimes it just whines without : > turning over before it kicks the breaker. With an extension cord, you : > can only restart it by bleeding off the back pressure. : >

: > There are two capacitors, a start capacitor and a run capacitor. : >

: >

: > The documentation states that the compressor warranty is void if you : > connect it to an extension card. And of course, if you run it without : > oil. : > info: : > Heavy duty 2.5 HP rated motor : > Air delivery: 5.6 SCFM @ 90 PSI; 7.2 SCFM @ 40 PSI : > Oil lubricated pump : > Thermal overload protection : > Dual capacitors for fast, easy starts : > Easy-to-read pressure regulator gauge : > Clear view oil window for easier maintenance : > High impact ABS shroud protects the motor : > CSA certified : > 120V, 60Hz, 3400 RPM; Single stage pump, 120 PSI max; Air outlet: : > 1/4''-18NPT; Weight: 65 lbs. : >

: > You think a hard start kit would help? : >

: >

: Starting current is very high on these motors. Extension cords cause too : much voltage drop at start. It says not to use a ext. cord right in the : manual! : : Also the 2.5 HP is BS. No 2.5HP motor plugs into a 15 or 20 amp

120 volt : outlet. The rating is bogus. ===> Sort of; it's "peak" hp, not continuous. Bass turds in marketing do that sort of crap.

: John : :

[Pop]

[Sherman]

The compressor(Item No. 90385-4VGA) works fine when plugged into a

115v outlet, but not when connected with an extension cord. Even a heavy duty cord causes the push-button circuit breaker to blow when it trys to restart after the pressure falls and the unit tries to kick in. When you push the button, the unit tries to start but kicks the breaker after about 1 second. Sometimes it just whines without turning over before it kicks the breaker. With an extension cord, you can only restart it by bleeding off the back pressure. There are two capacitors, a start capacitor and a run capacitor.

The documentation states that the compressor warranty is void if you connect it to an extension card. And of course, if you run it without oil. info: Heavy duty 2.5 HP rated motor Air delivery: 5.6 SCFM @ 90 PSI; 7.2 SCFM @ 40 PSI Oil lubricated pump Thermal overload protection Dual capacitors for fast, easy starts Easy-to-read pressure regulator gauge Clear view oil window for easier maintenance High impact ABS shroud protects the motor CSA certified

120V, 60Hz, 3400 RPM; Single stage pump, 120 PSI max; Air outlet: 1/4''-18NPT; Weight: 65 lbs.

You think a hard start kit would help?

[JohnR66]

Starting current is very high on these motors. Extension cords cause too much voltage drop at start. It says not to use a ext. cord right in the manual!

Also the 2.5 HP is BS. No 2.5HP motor plugs into a 15 or 20 amp 120 volt outlet. The rating is bogus. John

[Ralph Mowery]

I don't know what a heavy duty cord is. Unless it is # 14 wire or larger and about 25 feet long or less , you are getting too much voltage drop as the motor tries to start.

[keith]

2.5HP is about 1850W, or about 15.5A, so it *is* possible on a 20A circuit. ...though not likely. I have a 2KW bathroom heaters on 20A 120V circuits.

Though I agree, the starting current will be *MUCH* higher. Compressors are like that.

[Joseph Meehan]

I suggest getting a longer hose and don't use any extension cord. If you insist on an extension cord, accept nothing less than 12 gauge and as short as possible.

[George E. Cawthon]

Kind of sums it up. You should always being using a cord that is at least 12 gauge with a heavy motor and preferably a cord as short as possible.

However, I have a DevilBiss compressor 20 gallon,

5 hp (course it isn't 5 hp) that I have run on from a building that is powered by a 90 foot 10 gauge underground wire and the compress hooked to that with a 25 foot 12 gauge or 14 gauge extension cord. It has also run fine with extension cords in all of the outlets in the house (15 A circuits with 14 gauge wire) and some are fairly long. So I would say that compressor motor draws a lot of current at start, whether designed that way or because something is not right with the compressor circuit.

[John Willis]

On Tue, 13 Sep 2005 21:49:29 GMT, Sherman scribbled this interesting note:

You've had some good responses, but if I might, when (not if) this compressor goes south on you, and you are in the market for another, I'd suggest you spend a bit more money. Harbor Freight is fine for many things, including a compressor with which to air up basketballs and car and bicycle tires. If it is a compressor with which you hope to do much actual work, buy a good one. With excess capacity over and above what you will be using it for. And I don't mean go to Home Depot because most all their offerings come from the same kind of Chinese factory as what you already have.

When I need lots of air, I hook up two or more of the Thomas air compressors we use in our roofing business. Look them up. They are made in the USA and they last. The ones we run have no oil, use Teflon rings, and we've never had a motor burn up. And you can run them plugged into extension cords. (Although, as the others have already advised, I prefer using a heavy gauge cord.) These compressors are rated at 10,000 hours of use between rebuilds. That works out to eight hours a day, five days a week, for five years. We've never gotten rid of one of these compressors, although we've thrown away cheaper kinds like you would find at Harbor Freight or Home Depot!:~)

-- John Willis [e-mail] (Remove the Primes before e-mailing me)

[zxcvbob]

Another brand to look for is "Quincy".

Best regards, Bob

[Jeff Wisnia]

You are correct on the wattage, but you didn't include the motor's efficiency, and a NEMA B motor in the 1-4 HP range will have an efficiency of about 79%. So, to get the motor to produce a true 2.5 HP of mechanical output the current would be about 19.9 amps. That's theoretically possible on a 20 Amp circuit, but really pushing it. :-)

But almost everybody in the "shop world" knows that there was and still is far too much liberty taken with HP ratings on compressors. It was so bad that class action suits were started and settled in favor of purchasers:

Your 2KW bathroom heaters are 100% efficient and thus should draw only

16.7 amps on a 120 volt line, certainly OK for use on a 20 amp circuit.

Particularly when they don't have an "unloader valve" and have to start against tank pressure.

I just realized it's a little like trying to PUSH a nail into wood with a hammer, it works much better if you get the hammer moving BEFORE it touches the nail head.

Jeff

[Ulysses]

Many compressors will not start with an extension cord. I suggest you get a longer air hose.

[Don Klipstein]

Also, motors are said to typically have a power factor of .8. So that

19.9 amps becomes almost 25 amps (for a supposedly typical figure). Heaters have a power factor of 1, hardly less if they also have a fan or electronic controls.

- Don Klipstein ( [e-mail])

[Jeff Wisnia]

Well, I definitely overlooked the power factor issue, and I won't even try to BS you by saying that it's because I've fitted power factor correction capacitors to every motor in our home. :-)

But while I'm bloviating on the subject, during the energy crisis in the

70s, some guys at China Lake looked into improving the efficiency of fractional horsepower induction motors by putting an AC capacitor across the starter switch contacts, which rurned the motor into a two phase one as soon as those switch contacts opened. 20% eenergy savings were reported when using this technique on motors with relatively constant loads.

When that energy crisis cooled off that idea went away too. But I always tought it was a darned clever approach.

The only reference to it I've seen is a letter published in Electronic Design magazine in 2001, the last one on this page:

Jeff