Electric air compressor help?

I could use some advice on a Westward air compressor. It was made about 2004-ish and served a few years in a wet environment being used for a few minutes every few days. It was not in constant run use.

Lately, the compressor is hard starting and tripping out the breaker on the electric panel. It has clean oil in the pump. I pulled then pump off the tank, and the piston is smooth with just a little resistance. I can spin the flywheel with my finger. I removed the top of the pump hoping to look down into the cylinder, but it looks like a reed valve right under the top cap. I don't want to go any further in case parts are NLA. Pretty clean at the top.




The motor is a Dayton, and it sounds like the bearing at the pulley end is just starting to squeal at start up. I pulled the capacitors, there I tried to discharge both of them a few times, but they did not spark. I believe they should. The motor starts fine without the belt on the pulley wheel.



I tested the caps with a meter set on ohms 4m. The meter climbed steadily, so I believe, they are good. I'll read up more on testing them.

The pressure switch works fine, I need to replace the copper supply tube going to the tank. It holds pressure fine, but the copper is pretty crusty.

I'm leaning that the motor may just be worn or moisture has degraded some internals. If the caps are bad, I can replace them, but I would rather put the money towards a motor. I've put really nothing into this, so if it is the motor, I would consider replacing it. Most of the wiring contacts are a little fouled from years of moisture and could stand some cleaner. Not sure if this would help.

I mostly use my pancake compressor, but I'd like to use this one for my impact gun and air shear.

Any thoughts or maybe something I should look at with the motor? How about testing the capacitors? Thank you if you have any thoughts.

 

Your capacitor testing sounds like they are good.
Not sure what kind of meter you have but check motor winding to ground on the lowest resistance setting and work up to until you get a reading.

 

I'll look into the windings.

 

Another thing assuming you're running it at 120v is the FLA is 15A make sure the receptacle is 12gauge 20a, long runs on extension cord and it could be approaching thermal overloads

 

Start in the 400ohm range and work up

 

I thought of that a just a while ago. It is for the washing machine circuit. This could be a possibility. No ext cord, direct plug in. I have a short run to the kitchen 20 amp circuit I can try. I'll give that a try when I put this back together.

 

No go when I plugged it into a 20 amp circuit. I pulled the caps and tried to de-energize them, but they did not snap or spark when I crossed the prongs. I'm thinking the starter cap is not getting energized to kick the motor.

I found a video on the tube about the centrifugal switch could have corrosion or burnt contacts. I'll clean the contacts with emery cloth and I will definitely replace the spade connectors. They are covered with corrosion and I wonder if it is causing additional resistance.

 

Is the motor turning over at all when plugged in? If its a bad starter cap or switch(that one looks pretty rough) it will normally hum.
At least you have the motor end bale off - normally you get that point and the screws start snapping.

What were the motor winding readings? you can check from the hot or neutral to the ground prong if its still wired. Then check the winding & entire starting switch continuity by checking resistance on your lowest setting across hot-neutral. Its best to start from the plug as you can split the circuit at the pecker head incase its a bad plug/cable.

 

Motor runs with the belt off. With the belt on, it tries to go, hums and trips the breaker. I'd say the cap is not kicking it along.

I still have to check the motor windings. This is where it gets a little technical for me, so I need to grab a cold one and trace the wires and clean up the switch contacts and other components.

 

When you run it with the belt off as it starts you will hear a click of the centrifugal switch for the starter cap and again as is spools down.
The start capacitor gives the motor the phase shift it needs develop enough torque to rotate with a load and the switch takes it out of the circuit, the run capacitor just balances out the inductive load of the motor windings - keeps the power company form having to push excessive VARS or switch in cap banks.

 

It does click when it runs without the belt. The switch actuates well too.
I would assume that when the pressure switch calls, the start cap is energized. When the centrifugal switch spools up it actuates from the start to the run cap. Seems that power is not getting to start cap initially. I think that is where I need to look at those contacts.

 

You have a motor that will start and run when it is not under load but under load wants to trip the breaker. Testing the caps is how you did it; discharged the cap is going to be like a short and then as it charges tends to be an open circuit. The other thing would be the capacitance value but you need a capacitance checker for this.
Check the line voltage to make sure it is where it needs to be. The motor lists 15 amps at 120; so if your breaker is a 20 amp circuit you know that isn't the problem. If the caps are good, the load (pump) is not binding.... Oh, make sure air can flow through the discharge tube on the pump; I think you had already tested the pump disconnected so it isn't a stuck valve in the pump that is causing a high load but maybe the discharge tube is blocked. Sounds stupid I know but such happens. If everything checks good but the motor keeps tripping breakers under load my thoughts would be a bad winding in the motor.

By the way; if the motor is good; and you might want to take the motor to an electrical shop for testing, I suggest wiring a 220 circuit for the compressor. Your house has 220 volts and all you need is some 220 v cable and a 220 volt ganged breaker or even just two separate breakers and your compressor will be more efficient.

 

To test a capacitor hook a 110 test lead to the cap. Put a ammeter on and plug it in, record the current. Put a voltmeter on and plug it in, record the volts. 2650 x amps ÷ volts = mfd. This works for both electrolytic (start) and dialectric (run) caps.

 

Some good news to report. I ran it with the supply line from the pump to the tank disconnected and it still was tripping the breaker. Put the connection back.

I replaced all the spade disconnects that were covered in corrosion. I could not locate the disconnects that wrapped around the wire insulation and bare wire. I ended up soldering the disconnects to the wire leads. The start to run switch contact was cleaned with emery cloth again. Here are the old disconnects showing what a wet environment can do.


It finally ran and tripped after about 10 seconds. I noticed sparking in the pressure switch housing.

I pulled all four, crimped them and reset them. Now it ran until the pressure was satisfied. For chits, I tried discharging the start cap, and it would not spark. I am thinking of just replacing the cap.

basod, I did not check the resistance on the windings as there were a few wires in there and my lack of motor wiring knowledge is a stumbling block right now.

I'll replace the plug as it has evidence of shorting.




I have to believe that with all the corroded connections, it was causing a bit of resistance. I also think the start cap may be an issue. For short money it may be worth replacing.
Thank you to everyone that gave advice, truly a great forum with all the knowledge here. I'll give this compressor some love and clean up the rust.

 

fishingpol I have same stumbling block, followed cause I figured you were in good hands..

 

I also believe that the vibration from the compressor over time loosened some connections, combined with the corrosion were big factors.

 

The cap will discharge as soon as the centrifugal switch closes when the motor slows. If you want to see it spark on discharge you can short it while the motor is running right after the switch opens.

 

Ah, that explains a lot. Thank you for that info.

 

If you do get a new cap save the old one so you can charge it and leave it out for the people who always touch your stuff.

 

Hahaha.