# Forum Home Renovation Pools, Spa & Water Features  Diagnosing a humming and not starting Pool Pump

## DaleBlack

Hi I have a Astral CX180 pool pump, it was humming then stopping then after a time (assume auto cut off due to heat) starting. Now its just hums, stops, after a while tries to start again, hums - no starting. 
Before I get a new pump, I thought I would try replacing the capacitor.  http://www.inyopools.com/HowToPage/h...capacitor.aspx 
 Electrical testing wise, ie. ohms on a multimeter, can I test both the capacitor (though I don't mind just replacing it) but also assume the capacitor is new, what readouts can one perform on the motor itself with a multimeter?   
Probably cant be a fusion insurance claim unless the motor has burnt out.  
Note I can insert a flat blade screwdriver in the back of it and it turns fine. 
You can pick up replacement motors for around $440-600, so replacing the bearing at $220 like one pool shop quoted is not really worth it. 
thanks

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## droog

If you want to test if the start cap is at fault just manually spin the shaft of the pump while it is turned on, if the motor then runs it is the cap. 
Multimeter wise it is not so simple to test capacitors, the above test is easier.

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## NRB

I don't think it's a electrical issue,had the same problem,I will bet you have junk in the pump impeller.
You can turn the motor by hand but the starting load is too great for it to start,believe me it doesn't need much to be in there for it to overload.
The clearance is small and the final filter will let junk through.
Pump hums then oveverheats and stops 
Starts again when it cools down .
And so it goes on. 
Clean it out before you spend any more time or money.

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## NRB

It's not an electrical problem,there will be junk in the pump impeller,it doesn't take much to overload the motor into thermal cutoff 
Motor will not start,shuts down,cools down,tries to start,shuts down,etc,etc
had the same problem fixed after a clean out 
Not a lot of clearance in the pump impeller, the final filter still let's junk in.

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## DaleBlack

Fixed. 
It was the capacitor after all. 
I bought a Jaycar $16.95 capacitor  Motor Start Capacitors - 20uF | Motor Start | Capacitors | Passive Components | PRODUCTS | RU6606 | Jaycar Electronics 
fitted it, re fitted the pump, petroleum jellied the or rings, and the pump  kicks in straightaway, creepy climbing up the wall so no issue with pressure. 
The capacitor is bigger in size and didn't have a thread at the end but still fits inside the housing.

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## Random Username

That's a run capacitor, not a start capacitor in the motor.  The higher uf value means the motor winding current will be a little on the low side, so you may get some loss of performance/increase in power consumption.  https://www.youtube.com/watch?v=OMd9QkinXz4#t=146 
(generally, run caps are silver, start caps are black)

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## MorganGT

> That's a run capacitor, not a start capacitor in the motor.  
> (generally, run caps are silver, start caps are black)

  Actually it's much more likely it's a start capacitor, considering its rating. The colour means nothing - all the motor start capacitors I deal with (on coffee grinder motors and espresso machine pump motors) are white.

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## Random Username

A 15uf rating is a little on the low side for a start cap on a 240 volt/3.5 amp motor...  Should be around 80-100uf.   
And the colour tip was told to me about six months ago when I was looking for (what I initially thought was) a start capacitor for my bandsaw.  
I popped in to Delta Electric Motor Repairs (who have been electrical motor service people in Canberra for at least the last 30 years, so I'm assuming they are a reasonably knowledgeable source) and said "Hi, I'd like a start capacitor like this one for my bandsaw..." (holding up old one) and the old guy there said "No, that's a run capacitor, if it was a start cap it would be black, what's the value?".  I said "17 microfarad," he said "Yeah, run capacitor".  (I then got given an explanation of why you need a run cap on a single phase induction motor).  
You'll probably find the caps on grinders/coffee machines are run caps, too, unless there's something that takes them out of circuit once the motor is up to speed. (see the linked YouTube video in my first reply for what happens to start caps that get left in circuit). 
See also: http://www.practicalmachinist.com/vb...8/?#post344248 and http://www.doityourself.com/forum/ai...ml#post1376646 or http://www.capacitorformotor.com/motor_capacitor.html if you'd like it from a mob that makes both types of capacitor for motor applications (Temco Industrial).

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## MorganGT

> A 15uf rating is a little on the low side for a start cap on a 240 volt/3.5 amp motor...  Should be around 80-100uf.   
> And the colour tip was told to me about six months ago when I was looking for (what I initially thought was) a start capacitor for my bandsaw.

  10 or 12.5 uF are the most common ratings on the start capacitors on the motors I deal with, which draw a similar current at 230 volts, and they are definitely start capacitors, not run capacitors.

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## Random Username

It's been decades since I've heard the clunk of a centrifugal switch inside a motor  (and centrifugal switches strike me as one of those 'really needs a modern approach' devices).  Do they switch them out with an SCR and a relay or something these days?  Or are they capacitor start/capacitor run configuration?

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