To avoid these ads, REGISTER NOW!

Trying to repair a window A/C

Karl_B

Well-known member
Joined
Oct 13, 2013
Messages
428
Location
Killeen, TX
I know a lot members' first instinct is going to be to tell me to buy a new one, but I wouldn't learn anything but how to open my wallet if I did that before I determined the problem. I intend to use this as opportunity to learn a little more about electric motors.

I have an LG LW5014 5,000btu window A/C, and it does produce a bit of coolness. The issue seems to be with the fan. It doesn't like to start spinning at all, but it will with a little push. It doesn't start on its own on either speed, and switching between low and high doesn't seem to do anything but alter the pitch of the hum from the motor. I don't detect a change in fan speed or air flow.

I traced power in to through the switches, and everything checks out fine. I used the capacitor testing function on my multimeter and found the same values printed on the capacitor. This leaves me to believe the motor is bad, but I would prefer to verify this.

There is a diagram on the motor that shows four of the five wires. The last wire is undoubtedly the ground. There is an yellow wire that shows to be run to a capacitor, and it was run to the FAN terminal on the capacitor. Orange was marked as one of the two LINE wires. It is run to the common terminal on the capacitor. The red and black wires are marked as switched from the other LINE, and as black being high and red being low.

With everything hooked up, I get the condition I initially described. I did notice that when I forgot to ground the motor, there was no noise or motion. I checked resistance between the wires with the motor completely disconnected. OL between black and orange, OL between red and orange, and 17 or so ohms between black and red. I admittedly don't understand the start circuit, so I didn't check any resistance there. Is this enough to verify the motor is bad? What should I know from these readings?
 
To avoid these ads, REGISTER NOW!

rockwithjason

Well-known member
Joined
Jan 8, 2006
Messages
2,633
Location
Las Vegas
The start circuit should have a centrifugal switch that is closed at below 60% of speed and open above 60% of speed. That switch connects the start winding of the motor and gives it the little push you are missing. Check that switch.
 

theoldwizard1

Well-known member
Joined
Feb 22, 2011
Messages
43,212
Location
SE MI
The issue seems to be with the fan. It doesn't like to start spinning at all, but it will with a little push. It doesn't start on its own on either speed, ...

Most fans use Oilite bearing. They do dry up over time. A couple of drops of very light oil on the shaft, next to the bearing, will get them running again for awhile.
 

theoldwizard1

Well-known member
Joined
Feb 22, 2011
Messages
43,212
Location
SE MI
The start circuit should have a centrifugal switch that is closed at below 60% of speed and open above 60% of speed. That switch connects the start winding of the motor and gives it the little push you are missing. Check that switch.

That switch is usually INSIDE the motor. Check YouTube or Google "motor centrifugal switch".

It must be a big motor, because most fan motors don't use a capacitor start circuit.
 

Brian_WK

Well-known member
Joined
Jun 30, 2015
Messages
1,177
Location
NE South Dakota
I'm assuming its a run Cap and PSC motor. Sounds like a bearing issue to me those motors have very little starting torque and when the bearings/bushings wear they sieze. Is there any shaft play, up down left right or in out? If so the motor is shot. If not disassemble the motor find bushings/ bearings and oil the wick if bushings. If bearings pull apart and repack with grease.

Brian
 
To avoid these ads, REGISTER NOW!
OP
K

Karl_B

Well-known member
Joined
Oct 13, 2013
Messages
428
Location
Killeen, TX
The motor part number seems to be 4681A20116S. It's 115V, .37A and I'm assuming the 4µF/240V denotes that capacitor start circuit. The there seems to be no play in the shaft and the bearings feel pretty smooth. I don't know how much effort it should take to spin the motor by hand, but I spin it slowly with almost no effort. I did leave out that there is a LOT of evidence of insect activity all over the inside of this unit. I was assuming that lack of cooling could've done some damage to the windings or something in the motor.

It looks like it's just got some folded over tabs to hold the two sides together. I'm going to split the case and see what I see.
 
OP
K

Karl_B

Well-known member
Joined
Oct 13, 2013
Messages
428
Location
Killeen, TX
I hope I'm going to describe this properly. There is a good amount of rust on the outside of what I assume is the stator assembly. It's mostly on the bottom half, but I'm sure it's not a sign of a healthly motor. The rust is partly to the area where the wiring enters the motor. I'm betting it has effected the starting switch that would seem to be in there.

I suppose the thing to do now it try to remove the stator from the case and inspect the switch?
 
OP
K

Karl_B

Well-known member
Joined
Oct 13, 2013
Messages
428
Location
Killeen, TX
While trying to inspect this thing for a good way to get it apart, I see a lot of corrosion on a small section of the winding. I think I may have found the problem.

Edit: Not just corrosion, but burnt wires in the winding. It looks like this is the end of my journey. I can't see me having the patience to rewind this entire thing.
 
Last edited:

theoldwizard1

Well-known member
Joined
Feb 22, 2011
Messages
43,212
Location
SE MI
The motor part number seems to be 4681A20116S.
Google is your friend !

4681A20116S was replaced by 4681A20116T. I found a few places on the internet, but you need to call and see if they have them in stock. Prices vary A LOT !
 
OP
K

Karl_B

Well-known member
Joined
Oct 13, 2013
Messages
428
Location
Killeen, TX
I knew what it would cost to replace it before the first post. I wanted to learn why I was replacing it. :D Thanks for all the help, everyone. I might just see if I can salvage on old Craftsman 1 HP motor now. I was much more willing to destroy a tiny Korean motor than the old American one.
 
To avoid these ads, REGISTER NOW!
Top Bottom