Heater fan repair

[Roger G]

I have a small heater fan marked Krups type 984. The fan motor and the
whole unit appear very clean and nothing seems burned or damaged. The
problem is the fan doesn't spin with power applied (it tries to spin,
turning very, very slowly). I can turn the fan by hand and it feels a
little stiff.

It seems maybe the motor just needs lubrication but I don't know how
to do it properly. Do I need to remove the fan blade to get at the
motor? How? Do I need to clean the motor bearings before adding new
oil?

Any advice from someone with experience would be greatly appreciated.

 

[Sam Goldwasser]

I have a small heater fan marked Krups type 984. The fan motor and the
whole unit appear very clean and nothing seems burned or damaged. The
problem is the fan doesn't spin with power applied (it tries to spin,
turning very, very slowly). I can turn the fan by hand and it feels a
little stiff.

It seems maybe the motor just needs lubrication but I don't know how
to do it properly. Do I need to remove the fan blade to get at the
motor? How? Do I need to clean the motor bearings before adding new
oil?

Assuming it's the typical shaded pole motor,

It's best to remove the fan blades and disassemble the motor to remve
the shaft from the bushings.

Then. clean out the gummed up bushings and the shaft, put a couple
drops of electric motor oil on the shaft and bushings, reassemble
in reverse order.

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[Ray L. Volts]

Assuming it's the typical shaded pole motor,

It's best to remove the fan blades and disassemble the motor to remve
the shaft from the bushings.

Then. clean out the gummed up bushings and the shaft, put a couple
drops of electric motor oil on the shaft and bushings, reassemble
in reverse order.

My experience with these motors is that relubes don't last nearly as long as
the initial period before the fan started binding. I've tried everything
from 3-in-1 oil, sewing machine oil, teles oil, silicon oil, PTFE fluid,
WD-40, etc.. Same story with all. I presume this is due to the sleeve
bearings wearing such that the shaft is allowed to wobble/shutter. Or
perhaps the factories use a highly specialized lube just for these motors.

Also, Roger, if this is the shaded pole motor Sam and I are assuming it is
and it has the stamped blades with rubber coupler, you must get the blades
reinstalled just right or the imbalance will cause annoying vibration/rattle
which also happens to add to the wear on the sleeve bearings.

 

[James Sweet]

I have a small heater fan marked Krups type 984. The fan motor and the
whole unit appear very clean and nothing seems burned or damaged. The
problem is the fan doesn't spin with power applied (it tries to spin,
turning very, very slowly). I can turn the fan by hand and it feels a
little stiff.

It seems maybe the motor just needs lubrication but I don't know how
to do it properly. Do I need to remove the fan blade to get at the
motor? How? Do I need to clean the motor bearings before adding new
oil?

Any advice from someone with experience would be greatly appreciated.

Just take it apart and put a few drops of sewing machine oil, 3 in 1
oil, or something similar on the shaft at the bearing and twirl it a few
times by hand to work the oil in then reassemble.

 

[James Sweet]

My experience with these motors is that relubes don't last nearly as long as
the initial period before the fan started binding. I've tried everything
from 3-in-1 oil, sewing machine oil, teles oil, silicon oil, PTFE fluid,
WD-40, etc.. Same story with all. I presume this is due to the sleeve
bearings wearing such that the shaft is allowed to wobble/shutter. Or
perhaps the factories use a highly specialized lube just for these motors.

Often they use porous bronze bushings which should work better if soaked
overnight in a cup of oil. I've found that automotive wheel bearing
grease works well when other oils don't as it's thick and sticks on it's
own.

 

[Sam Goldwasser]

My experience with these motors is that relubes don't last nearly as long as
the initial period before the fan started binding. I've tried everything
from 3-in-1 oil, sewing machine oil, teles oil, silicon oil, PTFE fluid,
WD-40, etc.. Same story with all. I presume this is due to the sleeve
bearings wearing such that the shaft is allowed to wobble/shutter. Or
perhaps the factories use a highly specialized lube just for these motors.

Also, Roger, if this is the shaded pole motor Sam and I are assuming it is
and it has the stamped blades with rubber coupler, you must get the blades
reinstalled just right or the imbalance will cause annoying vibration/rattle
which also happens to add to the wear on the sleeve bearings.

If they are a press-fit, you may be able to do this with the
blades in place if there is enough exposed shaft.

I do have to lube my 50+ year old heater fan every couple years.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

 

[Shawn D'Alimonte]

My experience with these motors is that relubes don't last nearly as long as
the initial period before the fan started binding. I've tried everything
from 3-in-1 oil, sewing machine oil, teles oil, silicon oil, PTFE fluid,
WD-40, etc.. Same story with all. I presume this is due to the sleeve
bearings wearing such that the shaft is allowed to wobble/shutter. Or
perhaps the factories use a highly specialized lube just for these motors.

I notice the same. I find motor oil works pretty good. I use SAE30
from the lawnmower, but 5W30 or 10W30 from a car should work too (but
would be thinner at 'low' temperature).

 

[Roger G]

I have a small heater fan marked Krups type 984. The fan motor and the
whole unit appear very clean and nothing seems burned or damaged. The
problem is the fan doesn't spin with power applied (it tries to spin,
turning very, very slowly). I can turn the fan by hand and it feels a
little stiff.

It seems maybe the motor just needs lubrication but I don't know how
to do it properly. Do I need to remove the fan blade to get at the
motor? How? Do I need to clean the motor bearings before adding new
oil?

Any advice from someone with experience would be greatly appreciated.

Thanks to everyone who posted suggestions. They all seemed good and
encouraged me to try lubrication.

It was not possible for me to remove the fan blade without doing
damage I couldn't repair so access to the motor shaft was difficult.
Then I noticed there was a plug in the heater case that was easy to
pop off, and under the plug was the other end of the motor shaft.

First I tried 3-in-1 oil, and that made the fan feel less stiff, but
under power it didn't rotate fast enough. I then tried WD-40 and that
worked great. The fan now turns at full speed and the heater appears
to be working properly. Let's see how long it lasts.

Thanks again for the help. This is a great group.

 

[Sam Goldwasser]

Thanks to everyone who posted suggestions. They all seemed good and
encouraged me to try lubrication.

It was not possible for me to remove the fan blade without doing
damage I couldn't repair so access to the motor shaft was difficult.
Then I noticed there was a plug in the heater case that was easy to
pop off, and under the plug was the other end of the motor shaft.

First I tried 3-in-1 oil, and that made the fan feel less stiff, but
under power it didn't rotate fast enough. I then tried WD-40 and that
worked great. The fan now turns at full speed and the heater appears
to be working properly. Let's see how long it lasts.

The WD-40 won't last too long since it's not a good lubricant.

You'll want to clean up any WD-40 you can get to and then
use real oil. Almost anything is better than WD-40.
WD-40 is only for immediate gratification assuming someone
else will have to deal with the consequences down the road.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

 

[James Sweet]

Thanks to everyone who posted suggestions. They all seemed good and
encouraged me to try lubrication.

It was not possible for me to remove the fan blade without doing
damage I couldn't repair so access to the motor shaft was difficult.
Then I noticed there was a plug in the heater case that was easy to
pop off, and under the plug was the other end of the motor shaft.

First I tried 3-in-1 oil, and that made the fan feel less stiff, but
under power it didn't rotate fast enough. I then tried WD-40 and that
worked great. The fan now turns at full speed and the heater appears
to be working properly. Let's see how long it lasts.

Thanks again for the help. This is a great group.

The wd-40 is good for flushing out the old dried up lube, but you'll
want to stick some good oil in there after that. Also you have to be
very careful using something as flammable as WD-40 in a heater, you've
already powered it up but normally I'd say make sure it's well
ventilated first.

 

[Ray L. Volts]

Thanks to everyone who posted suggestions. They all seemed good and
encouraged me to try lubrication.

It was not possible for me to remove the fan blade without doing
damage I couldn't repair so access to the motor shaft was difficult.
Then I noticed there was a plug in the heater case that was easy to
pop off, and under the plug was the other end of the motor shaft.

First I tried 3-in-1 oil, and that made the fan feel less stiff, but
under power it didn't rotate fast enough. I then tried WD-40 and that
worked great. The fan now turns at full speed and the heater appears
to be working properly. Let's see how long it lasts.

Thanks again for the help. This is a great group.

As others have suggested, WD-40 isn't the best bet, especially where the
motor will be exposed to higher-than-usual heat. The heat will get rid of
the WD-40 jiffy quick. I bet it also stinks to high heaven -- not a super
good idea to breathe the fumes, either.
For high-heat applications, you might go with silicon oil or PTFE (teflon)
fluid.

If you now have both 3-in-1 and WD-40 in there, expect it to last an even
shorter period. The WD-40 breaks up the oil and it will gunk it up in no
time (the heat helps this along). Before trying the next lube type, clean
the motor thoroughly and only use ONE lube type at a time (i.e., don't mix
lubes).

 

[none]

Thanks to everyone who posted suggestions. They all seemed good and
encouraged me to try lubrication.

It was not possible for me to remove the fan blade without doing
damage I couldn't repair so access to the motor shaft was difficult.
Then I noticed there was a plug in the heater case that was easy to
pop off, and under the plug was the other end of the motor shaft.

First I tried 3-in-1 oil, and that made the fan feel less stiff, but
under power it didn't rotate fast enough. I then tried WD-40 and that
worked great. The fan now turns at full speed and the heater appears
to be working properly. Let's see how long it lasts.

Thanks again for the help. This is a great group.

The fan most likely has either brass or steel one piece
bearings.(single ball that the shaft sits on and is nested in a mount
that has felt type oiler pads.)
3-in1 makes an small electric motor oil(sae 5-10w??) that you can get
at most any hardware store that'll do the trick. Just put a drop or
two on the shaft letting it run down into the bearing and onto the
felt pads. Be sure to oil both front and rear bearings.
Another brand of oil goes by the name of "Zoom Spout oiler" and can be
had at your local Ace hardware store. It comes in a white plastic
bottle with a pull out plastic drip tube, is a pure turbine oil and is
perfect for lubing those heater blower bearings.(Made by Norvey inc of
Santa Ana.)
Sometimes the bearings will be gummed up with dried oil and gunk and
willl need to be removed and cleaned to get the best results.(usually
a couple of retainer screws on the bearing collars and the whole
assembly will pull apart allowing removal of the bearing from the
shaft. It can be cleaned with just about any solvent, I use a good
brand of carbuerator cleaner myself.(just spray the bearings and wipe
with a lint free shop rag.)
Be sure to oil all mating surfaces lightly before reassembly.(be sure
to saturate the felt oiler pads as well.)
If the bearing is of the steel variety you can use a good grade of
teflon grease instead of oil, just coat the shaft and bearing surface
lightly.(brass bearings tend to absorb most of the oils from the
silicone which will result in the grease gumming up in the long term.)