The wonders of Harbor Freight (Air compressor)

[GASCo]

Hi all,

I've got this Harbor Freight compressor for about 4 hard, at times, years. It never wanted to start in cold weather (45F and below), it would trip the thermal switch. It was never a problem since I don't do much work in these temperatures anyway. If I had to start it I'd just use a heatgun on the head of the compressor for 20 seconds and it would start right up.

Up until this week. It will not start. I noticed it pulls 40 amps and turns slowly until the thermal switch pops. I thought the switch was giving up too early and bypassed it. Now it trips the breaker.

I took the capacitor off and reinstalled. It worked! For 1 cycle. Now it doesn't start.

I thought the capacitor was bad, replaced it and still no start.

It does start though if I remove the high pressure relief valve. And, although tricky, if I reinstall when it is running it keeps running. If I shut it off it won't start again. I can sp[in the motor by hand just fine. The compressor head doesn't seem to bind.

I'm leaning to believe the starter coil switch is bad, taking more speed than needed to shutoff. If it even has a starter coil switch (I think every motor has one?).... However, I think if the centrifugal switch was bad, the motor would actually spin fast, but trip the breaker because of the high load. The motor doesn't spin fast (with load) at all.

Os maybe the starting coil itself is bad?

This is the compressor:

And this brass valve on the head is the bypass valve that when not in place makes the compressor start:

 

[cowades206]

Centrifugal switch bad? After a few hundred starts the contacts may be shot.

I have an old direct drive compressor with the same cold start problem. Don't know why I never thought to use a lighter weight oil in the winter.

 

[theoldwizard1]

SWAG - It could be the centrifugal switch which cut in (and out) the start capacitor is not workinhg properly. (There are dozens of videos on this topic on YouTube.)

In your case it sounds like the switch is not resetting when the motor stops so that you are trying to start on only the run windings, which is why replacing the start capacitor did not help.

 

[GASCo]

Who'd guess.... This tiny motor does not have a centrifugal switch. I believe it doesn't have starter windings. It just relies on the starter valve to relief pressure until it's up to speed. Now I suspect the valve is bad. I'll replace that now. https://manuals.harborfreight.com/manuals/61000-61999/61454.pdf

 

[theoldwizard1]

Who'd guess.... This tiny motor does not have a centrifugal switch. I believe it doesn't have starter windings.

Then the Chinese have figured out how to use just a run capacitor !

It just relies on the starter valve to relief pressure until it's up to speed. Now I suspect the valve is bad.

Inside the Pressure Switch (#54) there should be a head pressure release mechanism in there that releases the the pressure in the cylinder head when there is no power.. Make sure it is working.

Many of the external component to Chinese compressors a "standard"/interchangeable. Cheap on eBay. That start valve is also called a Cold Start Valve.

After that, the only thing I can guess is something in the cylinder is binding.

 

[Cryptic1911]

We've had issues with ours not being able to start without tripping a breaker if it was plugged into a 15 amp. I think it's probably the same issue you have, but plugging it into a 20 amp gives it enough time to grunt and get it fired up

 

[GASCo]

Tks Cryptic. It's been always on a 20A circuit.

I assume it might be the starter valve but called quits on this piece of junk. I opened the pump's crankcase to disconnect the motor (when I was looking for a centrifugal switch before looking at the manual). Now the gasket doesn't fit the cover anymore. I tried RTV sealant and it keeps the oil inside. However, the original gasket has a curtain to avoid oil spilling out of the vent. Without it oil blows off through the cap.

I'm tired... Now I have 240v in the garage and found an US made older (2000) 60 gallon craftsman (individual motor and pump) for $300. I'm going to take a look at it early next week. It seems to be in great shape but I see some oil on the tank. Hopefully nothing is cracked...