Faulty fan motor

[Greenbeast]

I have this fan from one of my walk in freezers.

• On the bench with a 24v supply it runs.
• The machine puts out 25-27v when appropriate (with motor disconnected)
• The contacts of the motor connector make the continuity circuit buzz on the DMM (not sure if this is significant or not)
• The contacts appear to present 0v when the motor is connected (and should be running)

Is this fixable?
Currently having trouble getting blades off due to a rusted set screw on the shaft. But if necessary I will persevere.
A new bare motor is £100 and a new whole assembly is £200.

 

[davidroberts30]

Connect another 24volt load to the supply
Just because you have 24v doesn't mean you have power

 

[Greenbeast]

Connect another 24volt load to the supply
Just because you have 24v doesn't mean you have power

The unit is running with a replacement fan from a donor unit now, but I need both units working

 

[Greenbeast]

Fridge engineer can't figure it out.
Fan runs off battery but not on unit.
Unit will run another fan

Apparently the circuit board load tests the fan and will cut out of too high (I think), whereas two car batteries will supply almost any current

 

[milkloss]

Are there any capacitors involved? They would lower the starting current.

 

[Greenbeast]

Are there any capacitors involved? They would lower the starting current.

Nothing external to the motor or the board

 

[milkloss]

Maybe wiz it down to deeprose, hollington road, Hastings. Don’t know if they’ve shutdown now so ring first. Genuine good old boys that know their stuff. Rewinds etc.

 

[Highland Mule]

Could it be the orientation? Maybe vertical in that machine and lies flat on the bench? Would mask a worn brush perhaps, if that were the case.

 

[Greenbeast]

Could it be the orientation? Maybe vertical in that machine and lies flat on the bench? Would mask a worn brush perhaps, if that were the case.

Interesting yes! I did lay it flay to test and it is vertical in the machine. Both brushes looked fine, although did sustain a tiny corner chip in each before they were put back Is that enough to cause a problem?
I suppose i can borrow brushes from the working fan to test that

 

[towbar]

Measure current used by working unit and non working unit. Is the non working unit stiffer to turn?

 

[Highland Mule]

Interesting yes! I did lay it flay to test and it is vertical in the machine. Both brushes looked fine, although did sustain a tiny corner chip in each before they were put back Is that enough to cause a problem?
I suppose i can borrow brushes from the working fan to test that

One way to find out...

 

[Greenbeast]

Measure current used by working unit and non working unit. Is the non working unit stiffer to turn?

I don't really have a way to do that.
No, spins free

 

[Highland Mule]

I don't really have a way to do that.
No, spins free

A multimeter would. Grab one for a fiver and you’ll get hours of fun from using it.

 

[Fruitbat]

The fans went in my cold store at the back end of last year, first one stopped, closely followed by the second as it was working it nuts off trying to move air through the now half frozen matrix. The grub screws holding the fan to the shaft were imperial hex and extremely tight, we had to resort to cutting the motor shaft and punching the stub through. Both motors still spun but as soon as power was turned on they would blow a fuse. Replacements off the shelf despite the cold store being over 30 years old...

ACRS, Pershore sorted me out
FB

 

[Greenbeast]

A multimeter would. Grab one for a fiver and you’ll get hours of fun from using it.

Annoyingly the DMM I bought last year (fluke) doesn't do amps, also wouldn't that need the circuit interrupting to test?

 

[Greenbeast]

OK, tested it running vertically

 

[milkloss]

Interesting yes! I did lay it flay to test and it is vertical in the machine. Both brushes looked fine, although did sustain a tiny corner chip in each before they were put back Is that enough to cause a problem?
I suppose i can borrow brushes from the working fan to test that

Ah ha! Brushes you say. Try running a hacksaw or knife down the contact gaps on the commutator.

 

[mogman]

Is the motor dc?
I had a bit of trouble with some solenoids once got 24v on the tester and on a bulb but wouldn’t work the coil, it was a diode gone in the rectifyer so sending ac to the coil when it needed dc

 

[Blue.]

If you decide to give up and replace the motor I find the best way to get the fan off is cut the shaft off the motor,you can then punch it out in the vice without damaging the blades/hub.

Motor sounds lazy to me,replace with new.

 

[Greenbeast]

If you decide to give up and replace the motor I find the best way to get the fan off is cut the shaft off the motor,you can then punch it out in the vice without damaging the blades/hub.

Motor sounds lazy to me,replace with new.

I drilled out the set screw and hammered the shaft free. I may replace it yes, but at least I can do just the motor now instead of the whole thing.