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I bought a new air compressor from Harbor Freight (8-gallon, 2hp,) and last night I added oil to the fill line, opened all valves, and started it to run it for the break in period (30 minutes with no load, open valves on the tank.)

When I first turned it on, it shut off immediately (1-2 seconds.) I pressed the reset button, started it up again, and it ran a bit longer (3 seconds) and then shut off again. Each time it shut off, it took progressively longer for the reset button to be pressable (it gives a little click when it's ready to be reset.) This went on for 5-7 cycles until it finally stayed running (much louder,) at which point it ran for the full 30 minutes until I turned it off.

Today I changed the oil and went to turn it on again, and it was the same deal: several cycles of progressively longer short moments of quiet run time, and then it fired up and ran fine.

Is this normal for oil-lubed air compressors? Is this part of the cold start process, or should I return it as DOA?

  • I've never had a breaker trip on a compressor that I haven't overheated by running it too hard. I assuming you changed the oil based on the manufacturer's break-in procedure? Does it do the same thing if you haven't just drained and refilled it? – Comintern Apr 9 '16 at 2:25
  • Clarity: this is an electric-powered compressor, not gas, and the breaker is on the supply to the motor, right? – Daniel Griscom Apr 9 '16 at 2:40
  • @DanielGriscom Yes, it is electric. I believe it is on the supply for the motor, but it is in the plastic shroud, so I can't see for certain. – Mark Avenius Apr 9 '16 at 2:57
  • @Comintern Yes, I followed the break in procedure precisely. I have only had it two days, so no, I can't say whether it does it otherwise. – Mark Avenius Apr 9 '16 at 2:59
  • If oil was added to the crank case and it had a problem take it back fast. I have had really good luck with most tools from H.F. But have had a couple that I exchanged, maybe lucky but I have had really good luck with there tools in most cases. Not Snap On quality but at 10% of that price, and Thier return policy I still purchase a few tools there. – Ed Beal Apr 9 '16 at 3:10
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I would return it. It doesn't sound like a lubrication issue - it sounds like either the motor soft starter is bad, is not well paired with the breaker, or is simply not present on that model. AC motors can pull substantially more current on initial start, and I'm guessing that is causing the breaker trips. I don't mean to knock Harbor Freight (much), but higher quality compressors of that size and capacity aren't usually that much more expensive. You can obviously do an exchange and hope for better luck with a replacement unit, but if you are planning on any serious use of it, reliability is a huge plus. Nothing destroys a work plan for the day like having a bunch of air tools that you can't use because the compressor won't start.

  • I returned it last night, and today the new one fired up right away. Thanks! For the record, I don't intend on using it much; mostly tires and basketballs. The only reason I went up from a pancake to this one was so I would have the option to get air tools in the future, should the need arise. Hence, HF ☺ – Mark Avenius Apr 10 '16 at 13:20
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The increasing time to reset suggests that the problem is thermal, at least in the cutoff switch. Might be a bad cutoff switch but I'd bet the switch is accurately measuring amperage to the motor, and the amperage is too high. Which is weird because, pumping against 0 air pressure, motor load should be low. I can think of 3 possibilities.

  • your AC outlet is not able to supply enough current, and the voltage is sagging, and the motor is pulling more current to compensate. A Kill-a-Watt will tell the tale.
  • The compressor is mechanically binding up, and that is overworking the motor.
  • The motor has an internal problem, e.g. shorted armature coils, and that is making it overheat.

I suspect the latter. Give it a cursory test with a Kill-a-watt and then back to Harbor Freight it goes.

I'm one for buying a quality industrial grade unit on Craigslist. I do mean to knock Harbor Freight; they are at best single-use tools(which have their place), and at worst, good money after bad.

  • Thank you for the advice. I don't intend to use it much; mostly for balls, bike tires, etc. I only went up from a pancake to this one because the cost was negligible and having more cfm potential gives me the opportunity to get air tools should I decide to. If that time comes and this one doesn't suffice, I'm only out $50 more than I would have paid for the pancake. I just wanted to give you some background so you understand my rationale. Thanks again! – Mark Avenius Apr 10 '16 at 13:24
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I had similar issue, & it was a bad capacitor. Couldn't find a 150 µF axial mount replacement for a decent price, so went with 100 µF (I think anything from 100 µF to 150 µF will work) can type CBB 60 or CBB65 start & run capacitor ($5 - $10 on eBay.) Cut wires where they entered old capacitor, added female blade connectors and built new mount. Used caulking gun ($4) tube as holder, by removing handle & cutting to length. Removed 8 mm bolt from old capacitor & used to attach the caulking gun cradle to the old capacitor mount on compressor. Wrapped black electrical tape around new capacitor to provide firm fit, and added a wire tie to secure it to new mounting.

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If your harbor freight compressor has a LEFOO pressure switch, check the unloading valve on the side opposite the gauge. You should see a device that has a very fine needle projecting from the bottom. When the compressor turns off, the foot just below the needle rises and pushes on the needle unloading the compressor. My experience has been that the foot that operates the needle is bent slightly so firm contact with the needle does not occur. Use a wide blade screw driver and wedge it under the upper foot and apply enough pressure to bend it upward slightly

  • Hello, and welcome to Home Improvement. Do you mean that if this device fails then the compressor starts loaded, and that causes the breaker to trip? And, you should probably take our tour so you'll know how best to contribute here. – Daniel Griscom Nov 12 '19 at 20:37

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