4 speed exhaust fan issues

[2011laramie]

I'm troubleshooting the exhaust fan in the kitchen. It quit working a while ago and I finally got a chance to dig into it.

The fan has 4 speeds and only 3 years old. Speeds 1 and 2 quit working. The motor will kinda attempt to start on settings 1 and 2, the squirrel cage might twitch 1/8" of an inch, then just stall. On settings 3 and 4 it'll turn fine.

I pulled the capacitor out and checked it, it was fine, 25micro farads. I checked the supply voltage on the terminal connectors, all were fine. I now realize that I labeled the 1 terminal wrong, I labeled it as ground but really it's the neutral. Setting 4 is in the middle.

The fan turns kinda easy by hand but it doesn't spin excessively afterwards.

What would cause 2 of the speeds to quit working, but 2 work?

The fan is ridiculously expensive here in Canada... like the appliance shop wants $770 for a new fan assembly.

 

[Stuart in MN]

Is this the exhaust fan in the vent hood over the stove? If it doesn't seem to spin as freely as it should, the bearings may be gummed up from cooking grease so that it doesn't have enough 'oomph' to run at the lower speed settings. You can usually disassemble the motor, flush out the bearings with some sort of solvent and then use some light machine oil on them, but it's often a losing battle to try to keep those kinds of light duty motors running.

 

[dogdog]

mine is going for almost 30 years, just cleaned it last night. not the same fan as OP though..

as far as trouble shooting... looks like 2 of the coils are shot...

as far as troubleshooting... that terminal have 5 connectors? probably 1 is neutral and 4 is hot for different speed.... figure out which and check resistance , maybe between neutral and the other 4 terminals?? I am suspecting they are different taps of the winding type of split phase motors. or call the manufacture ?

 

[Norcal]

If parts of the windings have failed, it's either cough up the dough for a new motor or get used to having only 2 speeds, although those are not the only options.

 

[walta]

There are three parts in this system the motor the cap and the switch.

When a cap tester tells me a cap is bad, I believe it. When it says good, I still am suspicious.

It could well be the switch not supplying power to the correct wires.

I would first try a new cap. Then I would bypass the switch and see if the motor runs.


Walta

 

[wyliesdiesels]

There are three parts in this system the motor the cap and the switch.

When a cap tester tells me a cap is bad, I believe it. When it says good, I still am suspicious.

It could well be the switch not supplying power to the correct wires.

I would first try a new cap. Then I would bypass the switch and see if the motor runs.


Walta

Yeah bypassing the switch and wiring power directly to individual taps on the motor windings is a good next step

 

[2011laramie]

So if I start the fan on setting 3 and let it spool up, then drop it down to 1 or 2 it will stay running.

So what's up with that?

 

[walta]

So if I start the fan on setting 3 and let it spool up, then drop it down to 1 or 2 it will stay running.

So what's up with that?

To my ear this symptom sounds like bad bearings in the motor.

Fan motors have almost no starting torque especially the lower speed settings.

If the motor has sleave bearing disassembly, cleaning and lubricating will likely fix the motor.

If the motor had common ball bearings, they may be replaceable and will likely fix the motor.

If the motor has proprietary bearing lubricating will likely get the motor to work for some amount of time but at some point replacement is the only option.

Walta

 

[2011laramie]

Finally got around to taking this apart. The one bearing was/is shot. I managed to get it lubricated up with some electrical motor oil. Reassembled everything and it starts on low speed now nicely. I will order some new bearings and get it swapped out.

Thanks for all very good responses. Much appreciated.