Pump Hum - Century Centurion

[Mr Swepty]

Hi Guys first post. I did some Google searching and found the following post which seems to be the same issue i have.

http://www.poolspaforum.com/forum/index.php?showtopic=21561

Please excuse my ignorance, but i really have no idea what I'm doing. I can build an truck engine, but electrical has me clueless.

My pump suddenly started doing the same thing, it just hums, if i spin it by hand and then hit the switch it takes off and spins fast, but only hums if i try to start it normally.

I pulled the thing on the top of the motor, it looks like what the other guy pulled the 30UF capacitor. Now I'm not sure what to do with it. I have a meter, but what am i looking for regarding good bad reading, what do i set the meter to?

Also in the other post, one guy mentions "the start winding is open or just shot" What is that? Is that something i can take out and replace or clean?

Thanks,

Scott

[Mr Swepty]

The cap has some fluid come out of it... Here are a couple of images.

If i was to replace this, could it actually fix the issue or am i wasting my time. I guess what I'm asking, does the capacitor help the motor start spinning?

If yes, where the heck do i get one, i can't tell what's the part number..

[quantumchromodynamics]

You can get capacitors at any motor shop. Look under electrical motors online or in the yellow pages..

That type of motor uses a centrifugal switch for starting. On startup, the switch is closed, and as the motor reaches speed, the switch opens. Over time, the switch contacts get oxidized and don't make good contact. Clean the contacts of the switch.

Capacitor Check (Start or Run)

• Set ohmmeter at Rx 1K.

• Slip a heavy piece of paper between points on the switch.

• Discharge capacitor by touching the two terminals simultaneously with the blade of an insulated handle crewdriver

• Attach one probe to each terminal. Ohmmeter needle should move rapidly to right then slowly drift to the left. (Low ohm reading to high ohm reading.)

• If digital meter is used, readings should start low and rapidly increase to maximum value.

• Replace capacitor if bad.

TIP: The replacement capacitor must be the same MFD as the original. However, if the same voltage rating is not available it is acceptable to use the next higher voltage. Example; if a 370 volt unit is not available, use the next rating, 440 volt.

Reference 1

Reference 2

[Mr Swepty]

Thank for the reply. I looked over some of the reference material you attached.

Looks like my pump is the following:

According to that description it doesn't have a start switch. Sounds like this capacitor is what gets the pump started? Is that right? If not, where is this starter switch so i can get it cleaned.

Thanks again,

Scott

[Mr Swepty]

I think i found a replacement Capacitor online, but it's asking what the MICROFARADS (MFD) is? I don't see that on the sticker anywhere.

What is the 30UF value? Is that the same thing as MFD?

This is where i found some, but not sure which to get. The MFD thing is throwing me off.

Capacitor List

[quantumchromodynamics]

The "U" is actually the Greek letter Mu ("µ"), which means micro, which means one millionth. You have a 30 microfarad capacitor (30 µF) = (30 MFD). Make sure that the size dimensions match up.

I think that there is a switch in the back under the end cap. You have to remove the 4 long through-bolts and pull back the end cap to get at the switch. If the pump is old, the through-bolts can break due to corrosion and the torque from the bolts being so long, and you might not be able to reassemble the motor. Make a mark on the end cap and motor to make sure you can realign the end cap so that the through-bolts line back up with the holes.

Before removing the end cap, replace the capacitor, and check the impeller for debris to see if that will work. Sometimes the impeller will get clogged and that can create enough resistance to prevent the motor from starting since it has less starting torque than normal.

Type: This is a code for the electrical design of the motor. For example, A. O. Smith uses “CX” to identify its PSC (Permanent Split Capacitor) switchless design. Other codes are “CS” for capacitor start; “SP” for split phase and “UAK” for capacitor start/capacitor run.

What does your motor label say for "type"?

[Mr Swepty]

Type Show "CX"

I really appreciate the help. I'm going to replace this capacitor like you said first before i start pulling other things apart. I will also blow out the motor as best i can.

I will update in few days.

Scott

[quantumchromodynamics]

Ok, so the CX means that the motor is a PSC (Permanent Split Capacitor) switchless design. Your capacitor is a "Run" capacitor. There is no "Start" capacitor. Since there is no start capacitor, the motor will have significantly less starting torque than a capacitor-start motor.

Any excessive resistance could keep the motor from starting. You can check the impeller for debris by removing the pump basket and sticking your finger into the hole going to the impeller. The impeller should be clear of debris and easy to turn. Make sure that the pump can't turn on while you are reaching in by turning off the power at the circuit breaker.

Even though the motor is called "switchless", I still think that there might be a switch under the end cap that might need to be cleaned. That would be the next step if nothing else works.

FAILURE TO START

(MOTOR HUMS OR ATTEMPTS TO START)

■ Check voltage at motor line terminals. If voltage is inadequate to start motor, check for loose connections, undersized wiring, overloaded circuit or other causes of voltage drop.

■ Start switch contacts not closed when motor is not operating. Switch may require adjustment. Switch contacts dirty or pitted.

■ Capacitor (where used) is “shorted” or “open”.

■ Check motor windings for “open” or “short”.

■ Check for continuity through protector.

■ Turn the motor shaft by hand to get the “feel” of the motor. If the shaft feels tight or doesn’t turn smoothly:

• Check the bearings for smooth operation. • See if there is evidence of the rotor striking the stator.

• Check for internal corrosion, cracked end frames, clogged fan or other obstruction within the motor.

• Check pump for obstructions, binding impeller, or bent shaft.

Reference

I'm not sure that there is a switch. The motor is called "switchless", so perhaps it doesn't have one. The capacitor is involved in starting, so that is the best place to start. The above reference gives other things to check. The reference shows how to check the capacitor, windings and the protector (Thermal Overload).

[Beelzy]

Century motors burn up those Caps all the time. It should run $15-20.00 at a motor shop. Not too many Pool stores keep those

around anymore.

There is no switch in the newer Century motors so don't worry about cleaning anything else. I would keep an eye on that motor

though, as that's a nasty Blowout on that Capacitor.