AC Fan Dosen't Run

[mictas]

Well this is fun, two things I like to use often have become broken to some point.

Anyway, I have a AC motor from a fan that will no longer run, however the additional electronics seems to work just fine, that is after testing.

This motor seems to have five wires, please see this photo

or below.
I have ran my multimeter in ohms mode and I think the motor itself is okay, and here is what I got...

Between the wires:
White & Black - 297Ω
Red & Black - 0.257KΩ
Red & Blue - 27.3Ω
Red & Yellow - 129.7Ω
Red & White - 233.1Ω

However, the start capacitor seems a bit off. Please see this photo or look below.

Now it's labeled as a 2UF capacitor + or - 5%, well with how bad my maths is...

2x0.05=0.1
0.1-2=1.9

So, I am guessing that between 1.8 uF to 2.2uF should be okay, only when testing the start capacitor I was getting between 1.5uF and 1.6uF and no spark. Well at 450v you'd expect a spark.

I was wanting to check to see if I was correct, before waiting until I get some money next and buy a drop in replacement capacitor.

[Armadillo]

The capacitor is OK.
You can't rely on the component tester for any accurate result.
The fault is obvious. Save your money on buying new cap.

[mictas]

The capacitor is OK.
You can't rely on the component tester for any accurate result.
The fault is obvious. Save your money on buying new cap.

I did also use a capacitor meter and not just the LCR tester, which had the same resolute.

So what is the fault?

[Electro Detective]

You really need an insulation/megger tester to track down issues with fans/motors.

Also the capacitor may read ok but perhaps it's dropped it's mojo and just can't supply the goods anymore

[mictas]

You really need an insulation/megger tester to track down issues with fans/motors.

Also the capacitor may read ok but perhaps it's dropped it's mojo and just can't supply the goods anymore

Would attaching a variac to the capacitor wires to see if I can get the motor to spin for a short time, be a good idea?

I was thinking setting it to 120v, since here in Australia we use 240v on out mains?

[Dacke]

That looks like a run capacitor,  not a start capacitor.  Start capacitors are much higher capacitance and are taken out of circuit once the motor is started.  It's not like a room fan would need the extra torque from a start capacitor anyway.  If you pull a run capacitor out of circuit,  the motor should still operate albeit slower and less efficiently.   The capacitor is probably fine.

Those resistance values look very high for windings in a small fan motor,  they should be reading almost zero.

[Armadillo]

Agree, capacitor is OK, except for 68 watt fan on 230VAC, what do you expect the resistance to be?

That looks like a run capacitor,  not a start capacitor.  Start capacitors are much higher capacitance and are taken out of circuit once the motor is started.  It's not like a room fan would need the extra torque from a start capacitor anyway.  If you pull a run capacitor out of circuit,  the motor should still operate albeit slower and less efficiently.   The capacitor is probably fine.

Those resistance values look very high for windings in a small fan motor,  they should be reading almost zero.

[Dacke]

For a small fan?  Single digits on each winding has been my experience.  Common to the highest speed winding would be the largest value.

Edit - Just noticed but I think the bigger problem is that the white to black reading should be the lowest,  with red to black being the highest according to the schematic.  The readings taken are the opposite.

[mictas]

So...

White testing, I only tested the capacitor black wire and there are two black wires...

To power the motor it has a four pin plug, and on that I am getting nothing...

So, now I am guessing, the fuse inside of the motor has gone south?

[Electro Detective]

Disassembly time perhaps...?   

[Microcheap]

These motors should have a thermal cutoff. I am guessing from the picture: testing the resistance from the input connector (black?) to the white wire should give you a small reading, if there's nothing, then probably the fuse is open.
If you can open the motor it should be easy to test and confirm that.

[mictas]

Disassembly time perhaps...? 

Been there, done that, its just held together with a few screws, thank god. 

These motors should have a thermal cutoff. I am guessing from the picture: testing the resistance from the input connector (black?) to the white wire should give you a small reading, if there's nothing, then probably the fuse is open.
If you can open the motor it should be easy to test and confirm that.

Yea, when I was trying to work things out, that is when I fell apart. I'm okay with brushed dc motors, since the two I dealt with had missing brushes, but this I am afraid of cutting one of the wires.

After reading what has been said in this topic, getting a fuse and tapping in through the capacitor's black cable, in a sad attempt to  jerry-rig the thing.
I think I do know what happen, the pore wiring in my flat loosing it when I plug-in and fire up my air compressor x-x. Even the fuse in that thing was vaporized at some point.

[floobydust]

OP, your ohmmeter readings do not add up? Red-White should total Wht-Yel and Yel-Blue and Blue-Red.
Does this fan just hum, or need a spin to start or is it dead?

[mictas]

OP, your ohmmeter readings do not add up? Red-White should total Wht-Yel and Yel-Blue and Blue-Red.
Does this fan just hum, or need a spin to start or is it dead?

Dead, it dosen't make any noise.
I did have an update, the plug that connected to the control PCB also has a black wire. When I was testing, I had tested between the capacitor's black wire and not the one on the plug its self.

The plugs black wire, reads as NC... Yea, I should have checked that.

Inside of the motor:

[Electro Detective]

Do the copper windings pass the smell test of minute doses of magic smoke released ?

[Microcheap]

There is your thermal fuse (see red arrow) remove it to test if possible.

[mictas]

Do the copper windings pass the smell test of minute doses of magic smoke released ?

Nope, no burning smell 

There is your thermal fuse (see red arrow) remove it to test if possible.

That I guessed, after I took the photo, but thanks for pointing that out.

So, just cutting it out should solve it? (Well for test)

[lwatts666]

I know this is obvious, and you have probably checked this already, but does the rotor spin freely in its bearings? These small cap start motors have very little starting torque, and even stiff grease in the bearings can prevent them from starting.

I just had a similar symptoms on a similar looking motor. The original lube had gummed up, making the bearings stiff, but not seized. Flushed out the bearings with kero and lightly repacked with fresh grease, now all good.

[Microcheap]

So, just cutting it out should solve it? (Well for test)

Yes you can cut it out, but for test purposes, maybe you can just follow the cables attached to its leads going to the connector and then test continuity from the plug. I can not see clearly from the pictures but I think you have one black cable coming from the connector, passing through the fuse and then another black (?) Cable connecting to the capacitor's terminal, so testing between these two points should answer the question.

[james_s]

That looks like a run capacitor,  not a start capacitor.  Start capacitors are much higher capacitance and are taken out of circuit once the motor is started.  It's not like a room fan would need the extra torque from a start capacitor anyway.  If you pull a run capacitor out of circuit,  the motor should still operate albeit slower and less efficiently.   The capacitor is probably fine.

That's not always true, the PSC motor is very common in AC units, both for the fan and compressor. These use a permanently connected capacitor to produce the phase shift necessary to make the motor spin. The run capacitor is a fairly common failure too, at least on the central AC and heat pump systems. They often use a dual section capacitor with around 5uF for the fan motor and 50uF for the compressor so that capacitor shown very well could be the run cap. The one in my heat pump failed over the summer on the hottest day of the year, the motor would just sit there and hum.

Also those cheap component testers are surprisingly accurate, I bought one a while back expecting a gimmicky toy but it has really surprised me.

[mictas]

I know this is obvious, and you have probably checked this already, but does the rotor spin freely in its bearings? These small cap start motors have very little starting torque, and even stiff grease in the bearings can prevent them from starting.

I just had a similar symptoms on a similar looking motor. The original lube had gummed up, making the bearings stiff, but not seized. Flushed out the bearings with kero and lightly repacked with fresh grease, now all good.

Yes the fan its self spins freely, I did also check the space between the magnet and coils, I found nothing to cause it to stop spinning.

There is your thermal fuse (see red arrow) remove it to test if possible.

So I took off the cover and this is what I found.

So, just cutting it out should solve it? (Well for test)

Yes you can cut it out, but for test purposes, maybe you can just follow the cables attached to its leads going to the connector and then test continuity from the plug. I can not see clearly from the pictures but I think you have one black cable coming from the connector, passing through the fuse and then another black (?) Cable connecting to the capacitor's terminal, so testing between these two points should answer the question.

The photo above, shows what was hiding under the black thing. I still have yet to cut it out.
But I wanted to ask, if I should put the two ends together to see if they start.

A

[Electro Detective]

If you do decide to go that way, join them with a fuse that will cope with the start up and running current of 68 watts,

stand back...    switch on

and don't forget to wear glasses   

if you haven't got a fuse, perhaps a 70 watt light globe as a joiner. Try a 60 and 100w if no love.

You may have to do the guesswork for fuse values or globe, or both in series, I'm just guessing what I would try 

Either way it's Safety First  especially on a possible bin candidate

[mictas]

If you do decide to go that way, join them with a fuse that will cope with the start up and running current of 68 watts,

stand back...    switch on

and don't forget to wear glasses   

if you haven't got a fuse, perhaps a 70 watt light globe as a joiner. Try a 60 and 100w if no love.

You may have to do the guesswork for fuse values or globe, or both in series, I'm just guessing what I would try 

Either way it's Safety First  especially on a possible bin candidate

Lets do math for a fuse?

Okay, so we know that the voltage of the motor is 230v = V and power is watts = 68w and we go with P÷V=I

68÷230=0.295

So a 300mA 250v fast burning fuse?

[Armadillo]

It's a thermal fuse. The body is NOT conductive. No accidental electrical contact with anything resulting from vibration or abrasion.

For trial test purpose, you can directly link the wire and taped it. The Ohms look OK.

My advice is, don't put a fuse with exposed metal.

Use a isolating transformer [not a variac] if you want. The KVA is limited.

[mictas]

It's a thermal fuse. The body is NOT conductive. No accidental electrical contact with anything resulting from vibration or abrasion.

For trial test purpose, you can directly link the wire and taped it. The Ohms look OK.

My advice is, don't put a fuse with exposed metal.

Use a isolating transformer [not a variac] if you want. The KVA is limited.

Oh, my plan is to fuse the other two fans I own, so this doesn't happen again. But I plan to use one of three fuse holders.

https://www.jaycar.com.au/square-6-3a-240v-m205-panel-mount-fuse-holder/p/SZ2034
https://www.jaycar.com.au/low-voltage-10a-m205-panel-mount-fuse-holder/p/SZ2030
https://www.jaycar.com.au/low-voltage-10a-3ag-panel-mount-fuse-holder/p/SZ2020

And I have a few of these floating about https://www.jaycar.com.au/standard-duty-5a-3ag-inline-fuse-holder/p/SZ2015

BUT, how is my math for a 300mA fast burning fuse?

That and I built a dim blub tester.