Refrigerator overload protector problem

[deRoy]

Hi, I want an expert opinion cause I've seached all web to no avail.

I have an old fridge that can't start. Internet says this an overload protector problem because it tries to start then buzzes for exactly 10 seconds ( sounds like a locked rotor ) then a click is heard , it goes off for 2 minutes and the cycle repeats.

My question is where is this overload protector located, is it in the start relay that gives power to the compressor's start winding, is it inside the compressor itself, or is it in both? Because if the click is not heard from the compressor then it might be a faulty relay problem.

I know there are ways to check if the compressor has a problem but I am away now from the house where the fridge is located and where it is there are no warehouses and is a good 200 miles to get there. So I want to know before I buy a new relay.

Thank you.

 

[Averagesupernova]

Sounds like a stuck compressor or a bad starting capacitor.

 

[Averagesupernova]

I'll add to this a bit more. If the motor attempts to turn then it is not likely an overload protection relay. As I said before either the rotor is stuck or you have a starting capacitor/start winding problem. In air conditioning something that is used to switch a start capacitor out is known as a potential relay. If memory serves me it senses the voltage across the start winding and switches the capacitor out when the rotor has come up to speed. Schemes using a relay that senses current in the main winding can be used too. I would assume a refrigerator could use something similar.
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Several things could be happening. The capacitor could be shorted. Then the unit draws a lot of current and the overload relay does what it's supposed to do.
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The starting relay could be bad which causes the start winding to be in circuit all the time which would cause the unit to draw excessive current and trip the overload relay.
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To do anything besides troubleshoot this farther is guessing at which part might be bad.

 

[deRoy]

I'll add to this a bit more. If the motor attempts to turn then it is not likely an overload protection relay. As I said before either the rotor is stuck or you have a starting capacitor/start winding problem. In air conditioning something that is used to switch a start capacitor out is known as a potential relay. If memory serves me it senses the voltage across the start winding and switches the capacitor out when the rotor has come up to speed. Schemes using a relay that senses current in the main winding can be used too. I would assume a refrigerator could use something similar.
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Several things could be happening. The capacitor could be shorted. Then the unit draws a lot of current and the overload relay does what it's supposed to do.
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The starting relay could be bad which causes the start winding to be in circuit all the time which would cause the unit to draw excessive current and trip the overload relay.
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To do anything besides troubleshoot this farther is guessing at which part might be bad.

Very interesting.

I forgot to mention that there is no start capacitor ( I saw only the relay and compressor outside ) and the compressor was hot to the touch ( warm to be exact, I could touch it. )
The motor does not attempt to turn and no piston vibrations are felt ( only a buzzing sound like electric current through a transformer.)

Supposing there is no internal overload protection relay inside the compressor, would the external visible potential relay that you're mentioning switch on and off with a clicking sound if it were defective?

 

[Averagesupernova]

How many wires go into the compressor?

 

[deRoy]

How many wires go into the compressor?

3, 1 to common above, one to start winding and one to run winding below.

 

[Averagesupernova]

3, 1 to common above, one to start winding and one to run winding below.

This is from a schematic? How is the relay you refer to wired? How many terminals?

 

[deRoy]

This is from a schematic? How is the relay you refer to wired? How many terminals?

This from what I remember now from what I've seen a week ago when I was at the house. If I had the fridge now before me, I'd send you a photo.

I am trying to figure out what's wrong and save a buck. I don't want to buy a new relay, go back and find nothing's wrong with it because the compressor's stuck.

So, supposing there is no internal overload protection relay inside the compressor, would the external visible potential or thermal overload relay switch on and off with a clicking sound if it were defective?

 

[Averagesupernova]

This from what I remember now from what I've seen a week ago when I was at the house. If I had the fridge now before me, I'd send you a photo.

I am trying to figure out what's wrong and save a buck. I don't want to buy a new relay, go back and find nothing's wrong with it because the compressor's stuck.

So, supposing there is no internal overload protection relay inside the compressor, would the external visible potential or thermal overload relay switch on and off with a clicking sound if it were defective?

If the external relay is an overload relay (basically a circuit breaker) then it's clicking sound indicates to me that it is likely doing what it is supposed to. But you haven't determined whether the clicking sound is actually coming from the external relay correct? You need to determine if both the start winding as well as the run winding both draw current.
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I don't think anyone can here can solve your problems based on the information given. So far we know that there are 3 leads coming out of the motor which implies each a start and run winding. We don't know how the device you refer to as a relay is wired nor how many terminals it has. A true relay such as a potential relay will have more than two terminals. A two terminal device would be a circuit breaker and interrupt current to both windings I would assume.
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More than three leads on this relay implies it is used to interrupt current in the start winding at the appropriate time. Since we do not know which winding or both windings draw current we cannot tell what the failure mode is.

 

[deRoy]

If the external relay is an overload relay (basically a circuit breaker) then it's clicking sound indicates to me that it is likely doing what it is supposed to. But you haven't determined whether the clicking sound is actually coming from the external relay correct? You need to determine if both the start winding as well as the run winding both draw current.
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I don't think anyone can here can solve your problems based on the information given. So far we know that there are 3 leads coming out of the motor which implies each a start and run winding. We don't know how the device you refer to as a relay is wired nor how many terminals it has. A true relay such as a potential relay will have more than two terminals. A two terminal device would be a circuit breaker and interrupt current to both windings I would assume.
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More than three leads on this relay implies it is used to interrupt current in the start winding at the appropriate time. Since we do not know which winding or both windings draw current we cannot tell what the failure mode is.

It's quite alright... Any extra information you are giving me is very useful to me. I can remember that there were more than 3 leads in the relay. No, I haven't determined whether the clicking sound is actually coming from the external relay. Definitely, it's not coming from the thermostat!

Is there, in general, an internal relay inside the compressor? Basically, this is the only information that I need right now. If there is not a relay in the compressor, then the external's working fine right? So I must go down and check the compressor by measuring the resistance across the 3 leads, correct?

Ok, I'll do nothing before I determine where the failure is. I'll keep you informed when I find out...

 

[Averagesupernova]

I won't say whether the unit would have something internal or not. I suppose it is possible that the outside relay could contain a circuit breaker depending upon configuration. You need to find out if both windings are drawing current when it tries to start. A clamp-on ammeter is the tool of choice for this.

 

[jim hardy]

My question is where is this overload protector located, is it in the start relay that gives power to the compressor's start winding, is it inside the compressor itself, or is it in both? Because if the click is not heard from the compressor then it might be a faulty relay problem.

Can you post a picture of the compressor ?
A decade or so ago they looked like this. I've not touched the new computerized ones.

often there's a run capacitor there too, last couple Sears/Whirlpools i worked on it was 10 uf.

The compressor probably has thermal protectors inside and that's what you hear clicking.

That "start relay" is often a thermistor that disconnects the start winding after a couple seconds . When it burns out the compressor does what you describe.
Pull your "Start Relay" and examine it carefully - when they go there's usually a hole melted in the plastic on motor side and the terminals are wobbly.
They're about forty bucks from Sears online parts catalog and they're all over Ebay.

That physical examination might reveal your trouble without need of electrical measurements.

However - a locked compressor will give the same hum & click.

Here's a link to a DIY site that describes how to test them.
http://www.davesrepair.com/DIYhelp/DIYcmprtest.htm
He asks that his article be cited only in its entirety so i won't snip&paste..
See his home-brew test box. It's how i test 'em too.
CAUTION ---- It involves working with mains power. If you're not accustomed to such work, get qualified help...

 

[jim hardy]

Hi, I want an expert opinion cause I've seached all web to no avail.

Here's a youtube for you


Last couple i fixed were similar to this - a snip from about 2:17 into the video

first part he removed, at 1:45, was the capacitor. It is usually sold separately.

any number of sites will point you to the one for your fridge

 

[Averagesupernova]

For what it's worth: I have a dehumidifier that had a compressor that quit recently. Hadn't bothered to look at it but tonight I had a quick look. The compressor has three leads that go into it and one winding is in series with a capacitor and this capacitor IS NEVER SWITCHED OUT. If the compressor is supposed to run, then both windings get power constantly. No startup relay. There is a circuit breaker on the side of the compressor and in this case it has gone bad. What I have noticed is that this breaker will cycle when operating normally. What happens is there is a sensor that detects frost and cuts power to the compressor. If the sensor warms up then the compressor will start again. If this happens fairly quickly the pressure differential in the system makes it difficult for the compressor to start and the breaker trips. I had observed this since the unit was new. Under normal operation this breaker will trip as described and self reset after a few minutes. A crude method that eventually wore out the breaker. I bypassed it and watched it and all seems well. I will have a look to see if the breaker is affordable enough to gamble on a replacement and then decide to replace the breaker or throw the whole thing out.
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Please note that I will NOT leave the unit with the breaker bypassed.

 

[deRoy]

The compressor probably has thermal protectors inside and that's what you hear clicking.

That "start relay" is often a thermistor that disconnects the start winding after a couple seconds . When it burns out the compressor does what you describe.
Pull your "Start Relay" and examine it carefully - when they go there's usually a hole melted in the plastic on motor side and the terminals are wobbly.
They're about forty bucks from Sears online parts catalog and they're all over Ebay.

That physical examination might reveal your trouble without need of electrical measurements.

However - a locked compressor will give the same hum & click.

Here's a link to a DIY site that describes how to test them.
http://www.davesrepair.com/DIYhelp/DIYcmprtest.htm
He asks that his article be cited only in its entirety so i won't snip&paste..
See his home-brew test box. It's how i test 'em too.
CAUTION ---- It involves working with mains power. If you're not accustomed to such work, get qualified help...

Thanks a lot @jim hardy . That information is everything I need to know for now. Right to the point and exactly what I asked for. You gave me hope that it might be a minor thermistor damage, so I will buy a handy one now for 5-10 $, to have just in case when I go back.

 

[jim hardy]

You gave me hope that it might be a minor thermistor damage, so I will buy a handy one now for 5-10 $, to have just in case when I go back.

That's a fairly hefty thermistor with substantial heat capacity. PTC of course. I paralleled three or four inexpensive nickel-sized ones for my first experiment before investing forty bucks in the replacement part from Sears.

The compressor has three leads that go into it and one winding is in series with a capacitor and this capacitor IS NEVER SWITCHED OUT. If the compressor is supposed to run, then both windings get power constantly. No startup relay.

You might find a PTC thermistor in parallel shorts out that capacitor for starting , when it heats up the cap makes it a capacitor-run split phase motor.

 

[deRoy]

Thanks!