Compressor wont start, just hummms...

[RABRods]

I wired up the new mag starter on my 5Hp Saylor Beall today. I followed the wiring diagram. I went to start it and it will not spin, the motor or mag starter just hums but does not spin. It sounds like it is trying to spin and is either "seized" or theres not enough power.

I checked the belts are not to tight, and the motor spins very freely by hand. I am not sure where to start. I have checked voltages and everything seems ok. I also bypassed the pressure switch to see if that was the problem, yet I have the same humming and no spinning.

The motor is a 5Hp Leeson and has the capacitors on the top of it also.

Any help would be appreciated!! Thanks!

 

[Diver5855]

Check capacitor,my 2hp motor on my wood splitter did the same

 

[stonesfan68]

It sounds like the starting capacitor may be shot. You should turn off the power, wait for about 20 minutes, and then take a look at the capacitors. You can test the capacitors with a multimeter, I think. If they fail testing then you can search on-line for replacement parts. Grainger carries them.

 

[jkherd]

Check the capacitor and also the centrifugal switch on the motor shaft. If the switch isn't holding the contacts closed for the start windings then the motor will hum also.

 

[RABRods]

Hmm I didn't even k ow there was a centrifugal shaft sensor. I assume I need to take apart the case to get to it?

Also, I have the capacitors out now, yet how do I measure the resistance on a 4 terminal capacitor? I measured across the two terminals where the wires were attached and the value was 7.10mf. The capacitor lists 430-516MFD, so if I did that right I assume its bad.

 

[jkherd]

Here is a method to check a capacitor with a multimeter
http://www.wikihow.com/Check-a-Start-Capacitor

 

[awdblazer]

single phase or three phase?

 

[RABRods]

Single phase

 

[Gary S]

I wired up the new mag starter on my 5Hp Saylor Beall today.

I'm not sure I understand what happened. Did the compressor work before you rewired it? If so, go back to your wiring and leave the parts alone that worked before.

 

[RABRods]

The compressor was originally 3 phase, I replaced the old mag starter and three phase motor with single phase.

I have measured the capacitor and I am getting inconsistent or no reading. I am thinking it is the start capacitor, so I plan to pick one up at grainger on the way home and try that out.

 

[RABRods]

I replaced what I thought was a bad start capacitor...still have the exact same issue. I guess next is checking the centrifigul switch. I assume the only way to check that is to take the casing apart.

 

[tlfoster38]

I'm not familiar with your compressor. However, on my 120V compressor, it would hum on a 120v 15amp circuit, but worked fine on a 120v 20 amp line.

 

[Spareparts]

Try spinning the compressor pulley with the switch on and see if it starts, if so check the centrifigul switch.

 

[kams1973]

Take the belts off the compressor and see if the motor will start with no load.

 

[RABRods]

So I took the belts off and tried starting with no load. It still makes the humming/almost grinding noise, but just to start and moves slowly, then after about 3-4 seconds it kicks like I would expect it to and sounds quiet and smooth rotating att a "normal speed". I turned off and on a few times to see if maybe it just needed to "free itself" yet it was the same each time....So what exactly does that mean now??

 

[May Pop]

It hums because it doesnt know the words.

 

[laser3kw]

post pic of (new) motor data plate and over all wiring (inside box)if possible.

 

[RABRods]

The diagram is from Elimia the mag starter manf. The other pics are of the wiring and motor data plate.

 

[kams1973]

Bypass the starter assembly and see how the motor behaves, again with the belts off.

 

[Warrenator]

sounds exactly like what mine did with a gummy centrifugal switch. The switch is located on the end cap with the wiring, it is a brass doohickey with springs and contacts, all you have to do is wiggle it, make sure it is free, and lube it with oil, then clean the contacts with paper (drag a card through the closed contacts to scrape off corrosion and oil)

 

[laser3kw]

top connections look like "L1" "L2" "L3" - large black and large white are incoming from load center / breaker box -correct?

it looks like there is a "red wire" going to "t3" (lower right). The diagram does not show an additional connection there. What is it for?

 

[RABRods]

top connections look like "L1" "L2" "L3" - large black and large white are incoming from load center / breaker box -correct?

it looks like there is a "red wire" going to "t3" (lower right). The diagram does not show an additional connection there. What is it for?

Correct L1 & L2 are coming from breaker. L3 is connected to T1 (jumper since I am using single phase, the mag starter can be single or three phase).

the small red wire your seeing near L3 isnt actually on L3 it is connected to the "overload" area and I believe goes to the selector light/switch on the outside of the box, that part was all wired up by the manufacutrer. All I wired were the incoming (breaker) wires and out (motor) wires and connection to pressure switch.

 

[RABRods]

I will try bypassing mag starter and cleaning centrifigul switch tonight.

For "oiling" the centrifigul switch, should I use a di-electric grease?

 

[nehog]

...
For "oiling" the centrifigul switch, should I use a di-electric grease?

No lubricant.

 

[laser3kw]

here is the Leeson motor wiring diagram from the Leeson web site, for your motor, cat 131537. Are your wires from the box to the motor wired (clockwise):
starter T2 > motor lead T1 & T5
starter T3 > motor leads T4 & T8

 

[RABRods]

So I think my first problem is solved...but now I may have another issue.

As far as the first fix, the centrifigul starter seemed to be working yet it was the stationary switch not making contact to it, therefore allowing the start capacitor to actually kick. It was as simple as removing the rear cover and bening the taps out a bit to actually hit the centrifigul switch!.

Now that I did that, I re assembled the motor and have it just setting on the compressor (not bolted down) to test and seem if it starts before complete re assembly. It does start but now it sounds like it is running "dry" (maybe I am just over sensitive haha) do I need to dissassmble again and grease bearings, what type of grease, it looks like a green vaseline!

Second when I turned the motor off as it rocked a bit bc it is just sitting on the comp, the base of motor sparked between motor frame and compressor. Is this normal, and just becuase it is not bolted tight so it is looking for additional ground? I do have the motor gounded in the connection area from the ground bar on the mag starter which connects to ground in subpanel. Or do I need to add additional ground to the frame? Or am I once again overthinking it, and if it was bolted tight it wouldn't be a problem?