12 replies to this topic

[horn4life]

Goodman CKJ48-1AB

Thought that AC wasn't cooling 100%, and low and behold went outside and condenser fan was not turning and fan was hot as well as entire unit. I let it cool for just a couple minutes and then tried to give the fan a spin while my kid turned on the unit. Fan spun fine for a few minutes, the crapped out. I was unsure if perhaps having the fan unit so hot might have been part of the problem and causing the fan to shut down.

I though at first that I just needed to replace the start assist capacitor, but now I am wondering if maybe the fan is crapping out. It turns fairly easily, but seemed to come to a stop abruptly. Not grinding or hard to turn, but maybe not 100 percent?

So is there an easy way to test to see if the fan motor needs replacement? not an electrical genius but pretty handy. Already read about discharging the capacitor for safety.

thanks in advance

[RegUS_PatOff]

with power removed, try turning the Motor shaft by hand..using your fingers...
Does it turn easily, smoothly ?
Can you give it a twist, and it will continue for a few turns ?
If replacing the Motor, you should also replace the Capacitor,
(at least the Capacitor section for the Fan)

[Cactus Bob]

if the cap is bad the motor will not start on it's own at all ,
if the cap is bad you can give the motor a spin backwards , turn on power , motor will run backwards , it will be weak but will still take off backwards

the motor cap you have in your unit is not a start cap , it's a run cap

the way you said that the motor ran and then stopped quickly tells me a bushing / bearing problem , not a bad capacitor problem

[horn4life]

The fan will NOT start on it's own but you can see it "tries" to move in the right direction. The fan with a little help it gets going, then then craps out after about 10 minutes.

The fan motor will NOT run backwards at start with a reverse assist.

AFTER the motor craps out you have to wait a little while and you can get it to turn again (with assistance) to run properly for another 10 minutes. I don't want the compressor to overwork so I have been standing next to it waiting for it to die, then run in and shut down the unit down.

Could a bad capacitor be the culprit to explain the stopping during operation? OR is it more likely a problem with the motor?

When the motor craps out it doesn't make a noise or come to a grinding halt it just stops.

[RegUS_PatOff]

... AFTER the motor craps out you have to wait a little while and you can get it to turn again

seems like the Motor is over-heating.
When it stops, feel the Motor to see if it's hot.

with power removed, try turning the Motor shaft by hand..using your fingers...
Does it turn easily, smoothly ?
Can you give it a twist, and it will continue for a few turns ?
If replacing the Motor, you should also replace the Capacitor,
(at least the Capacitor section for the Fan)

[Cactus Bob]

The capacitor is fine

the motor is bad

100 %

[horn4life]

-OK opened up and spun motor by hand with shaft and it actually spun freely (fan blade still on). I was expecting it to not turn as freely...
-Motor is definitely hot when motor shuts down. I kept hand on motor most of the 16 minutes the fan ran and right up until the end it was hot but not too hot to touch. About the time it got really hot the motor shut down..
-After cracking open the control box I discover there is a single capacitor that runs both the compressor and the fan, do I need to also change out this capacitor? Or should I just replace fan and see what happens? I don't mind paying for both the capacitor and the fan motor, but of course do not want to spend more than necessary.

ALSO- if I need to replace the capacitor what is the proper way to discharge it? three post C, F and HERM.

Thanks in advance for your input- sourcing parts now...

Edited by horn4life, 05 October 2012 - 10:54 AM.

[RegUS_PatOff]

that's a dual Capacitor .. two sections .. one for Fan, one for Compressor
Could be about $ 50
OR just a replacement for the (smaller section) Fan Capacitor .. about $ 5
If replacing the Fan Motor, install a new Capacitor (matched to the rating needed for the new Motor)
C = common
F = Fan
HERM = (hermetically sealed) Compressor

I'm not a HVAC master, but if the run Capacitor was bad (or nearly 0 MFD)
might the Motor run, but then over-heat after a few minutes ?
OR not over-heat at all ?

[Cactus Bob]

the motor may spin by hand no problem ,even if the motor is bad

your replacement motor most likely will be a universal motor that will use it's own cap , that will be a 5 mfd to a 7.5 mfd . if you go with a oem motor it will connect to the cap already there

you do not need to discharge this cap , it's mfd's are to low to be of any danger , but be aware if you have a black plastic cap in there too (compressor start cap) you will need to discharge that one before you stick your hand in there

regus: newer caps do not get weak , its a good or bad with them , really old caps can dry out and get weak but this is not the case in this case . a really weak cap might start the motor and overheat it , but a bad cap will never be able to give the motor direction (the cap makes a phase shift in the delta type windings this gives the motor direction )

again i go back to the way the motor stops and a clue to the motors health , and it's not good

[horn4life]

Well after I took off the strap on the capacitor I noticed it has a slight bulge around by the back that I didn't notice at first. Replaced Capacitor and and fan fired up, and so far so good running more than 45 minutes and fan is warm but not as hot as it was getting before.

THANK YOU ALL for your input! Got lucky and looks like the cheapie fix was the right fix. Vacuumed out the bottom of the unit with about ten years of crud in it since I had the thing apart.

[Cactus Bob]

well , nothing like being wrong , glad you got it fixed

it's hard to get some of these things right sometimes going only by words typed on a page

what is free spinning to you might be tight to me or the other way around

it is rare for a cap to go bad half way

so i stand corrected

[jb8103]

That's a new one on me, too - a bad cap causing an overheat condition...I dunno, I think there might be a bit more to this one. Anyway, into the bag of tricks, although I always test them anyway.

[Shootist]

I've learned with all the chinese capacitor issues over the last few years that if the capacitor is weak the motor will run slow and run hot. I check the uF on the cap with my meter first thing. If you don't have a meter they aren't all that expensive. I've bought nothing but Amrad caps for 3 years now.