Yong hang compressor refuses to start, just hums

[MGH]

Hello everyone,
I’m new to forums such as this, but I’m hoping someone might be able to help me, l bought one of these Yong hang compressors and have been very happy with it up until when I went to use it last and it refused to start ( just hummed/buzzed) ok I thought, that’s easy it’s the start capacitor, so I tested it with a multimeter and it seemed fine, but I tried it with a brand new one of the same value but it’s exactly the same? The pump turns freely by hand so I’m out of ideas I’m afraid! I’m no expert on electrics but I know the basics, I’m wondering if anyone has had the same problem or knows how to test if the start circuit is bad!
Thanks in advance

 

[broekzwans]

is the motor itself turning when you here the humming noise? If yes then your crankshaft is broken (common issues with these compressor due to their single roller bearing).

if not: Normally the capacitor is used to create a phase shift inside a motor to start it and if one of the connections is loose it'll start buzzing and start to dissipate energy instead of powering the shaft and rotating.

there is no control circuitry in these compressors as far as I know so I think it has to be in the motor or the wiring.

 

[ohio_hunter]

my YH did that also,i would just wait a few and try it again and it turned on.do you have both air bleeds open when you try to start it?after using it(them)they started to function correctly.i only use oil that is recommended.

 

[Choc]

I just purchased one myself. It would hum for a sec, chug twice and stop. I moved it to an outlet closer to the electrical panel and it runs fine there. I guess the wiring in this old building is sub-par. I only mention that in case something in your environment changed, new location, trying to use an extension cord, etc. Also, when trying to trouble shoot mine it was not easy to turn by hand (using a narrow tool to turn the fan blades through the shroud). How long have you had yours? 

 

[oldsparky]

A humming motor is usually indicating a locked rotor condition. Start simple. Is the motor trying to start under a load. Bleed air. Can you turn the motor by hand, even the fan on the end bell of the motor. If not mechanical lock up. Then get into electrical. Is the voltage correct. If you have a starting capacitor is it good. 

Jim

 

[prfssrlee]

Hi there - all the above are good suggestions and things to check. I also noticed that when new, then semi-metal rings on the 2nd stage have to wear-in, and that generated alot of carbon black deposit on the 2nd stage piston. My YH struggled to overcome the added stiction from those carbon deposits after a couple of hours of operation. That is, just like you, mine ran fine for awhile then stopped working. I just popped the 2nd stage cylinder off, wiped the piston clean and reassembled. That did the trick. Nowthe rings are worn in so the piston stays clean.

 

[MGH]

Hi everyone thanks very much for your replys
i have only used it 3 times at 10 mins a time to top off a 3 litre cylinder from 3000 to 4500 psi
ive used the recommended #46 anti wear hydraulic oil and changed it twice already and keep the level just above the
red dot on the sight glass, I always start it with both bleed valves open and let it warm up for approx 30 seconds before closing them
then let the pressure reach just slightly above 3000 before I open the bottle valve so it equalises and it worked just fine!
As I live inEngland it’s a 240 volt motor, I’m using it from the same outlet I always have done ( not on extension lead )
ive tried bypassing the switch and relay and put 240 volts straight to the motor lines with the same result it just hums!
this really frustrating, the live and neutral lines are continuous going to the motor
and with the capacitor removed, there is continuity from live to both of the cap lines coming from the motor windings (if that makes sense)
and it’s also continuous from the neutral line to both of the cap lines from the motor!
like I say I’m no expert at all, does anyone know of any other tests I could try?
the pump is free and turns over by hand
Thanks for all your help guys

 

[LSS152]

Is it plugged into an extension cord? Try it directly into the outlet. The extension cord my not be enough to carry the electricity it needs to run properly. (Sorry looks like you already address the cord) Disregard my comments

 

[Centercut]

Hmmmm, that #46 anti wear hydraulic oil is for hydraulic systems, kind of like your brake system in the car or other things operated hydraulically. I'll bet it turned jet black very quickly? I would disassemble the compressor and check the first and second stage and check the rings and condition of the cylinders. When you reassemble it, use compressor oil, like the Royal Purple Synfilm Air Compresssor oil that is sold on Amazon.com.

 

[MGH]

Hi prfssrlee,
Thaks for the idea, I took the 2nd stage head off,and yes it was a bit black and oily so I cleaned it, I tried to start it with the head completely off it with no resistance whatsoever but it still just hums,even with spinning the fan round by hand it still won’t start! 

 

[ohio_hunter]

i use the #46 anti wear hydraulic oil and it hasn't turned black yet.can you still return the unit?

 

[MGH]

Fortunately, I got onto them about it and they said if I take it to a repair shop they will pay the bill, or if I know someone who knows what their doing they will supply the parts free of charge! So I told them I need a new electric motor ( stator and rotor ) so their going to send me the parts
ill keep you updated on how I get on! They seem to be very good and stand behind their product!
ohio-hunter, the first time I ran my compressor I drained the oil out and took the crank cover off and cleaned it out, there was some metal swarf in the bottom birectly under the crank/big end, and in suspension in the oil,so I drained it the next time I ran it, the oil was a lot cleaner this time. I’ve run it (all of 3 times) the 3rd time the oil looked just as clean as when I changed it, so it’s definitely worth changing it for the first two break in times cause you certainly don’t want that soup of metal swarf getting between the bearing faces!