If you can disconnect the motor from the pump, see if the pump turns hard by hand, you may have a corrosion issue. Also see if the motor runs without overloading when disconnected, it could be a motor bearing problem.
Hopefully, you can fix it without needing parts as you would probably have a hard time finding anything that fits.

thanks...will check. HF has the parts for about $60, but a 6-8wk lead time. egads.

Yeah the wait time isn't great - what parts are they saying you need, have you definitely isolated the problem?

On the other hand, you did get 5 years out of it. Sometimes things are better being used more often, sitting idle can be bad for some stuff.

Hope you get it sorted out. It should be fairly simple from the sounds of it.

HF thought the motor needed replacement ($45) and I thought I should maybe replace the capacitor ($11) and some relay switch ($1.50) +s/h...guesswork at its best.

The compressor was operational for the last couple of weeks. Then last night it runs for 3-5 seconds and trips its breaker. Technically, I could sit there for an hour resetting the breaker and filling the tank in 3-5 second increments. What I don't understand is if the motor is no good, why does it even run?

If the motor - perhaps the bearings are bad, it may run for a bit then overheat.

I don't know much about a/c motors, but it could also be the capacitor.

Did you try to see if the motor was turning freely or not?

I guess the other possibility is the motor's fine, and something in the compressor part is stiff or seized up. If you can separate motor from compressor, try both to see if they turn freely. If they do, try replacing the capacitor first. You may not need to deal with HF for that, they are usually fairly common items, you could go to a specialty electric wholesaler, or a motor rewind/repair place, they should have them.

If it was the capacitor, switch or motor it wouldn't run at all. My guess is the bearings in either the motor or pump, especially if they are the sealed-never need lubricating type.

Don't forget the oil less type motors don't hold up will to hard or continuous use if that is the type you have. The oil type are slower but better. Take a look at what a local Mom Pop electric repair shop can do for you. Chances are they can't fix it but if they can it might be cheap and if a new motor is in order you might get one for less than the Chinese parts. I replaced the blower motor for my trailer furnace like that for 1/3 what one cost from the trailer supply or anyone else and guess what it was a Dayton. It is worth a call. Come worst you might be able to get a new air unit and mount it on the tank easier / cheaper. I have had a HF Campbell Hausfield 10 years now, ok but no prize and way CFM over rated.

There's chineese made stuff and then there's the whole line of Central/Harbor Freight crap. I used to have a business partner that loved to buy that stuff. Not a single one was worth it. I've got real unkind things to say about the*@($% drill press as well. Not only not functional, not safe.

Whats the amp draw?

Could just be the $1.00 cheapo circuit breaker on the unit

I'm betting on the cheapo little overload protector, Had several fail over the years on diff. brands of compressor. Unplug the thing, pull off the plastic cover and jump across at the overload protector. be carefull, fan will spin when you plug it in. Bet it builds to full pressure and cuts off. Jim