View Full Version : AC vibration
I have an old AC unit in my house, Heat Controller, Inc. model SU30-1B. I'm guessing about 20 years old. It works fine and cools sufficiently. However, the condenser unit vibrates quite visibly.
Qustions: 1. Is the vibration normal or an indication of impending failure? 2. If not normal, what should I look for?
Info: Motor is GE 1/5 hp model 5KCP, unit sits on Bramec Air-Pad on top of landscaping gravel. 5-bladed fan does not appear damaged.
Any input would be appreciated.
07-15-2005, 12:42 PM
1st thing to check for are loose compressor mounting bolts/screws.
07-15-2005, 12:53 PM
second thing is is it mounted to the pad via tapcon's or similar? As a last resort, I used pipe strapping on an ancient Carrier where the bottom was rusted out,strapping it across the top of it to the pad.
No, it is not mounted to the pad at all just sitting on top of it. The pad is foam with a thin plastic skin so I doubt it would hold any screws. My other AC (a newer Carrier) sits on an identical pad, also not fastened, just a few feet away and vibrates not at all.
I will check for loose compressor later today when it's cooler and I can turn it off.
Is there a way for the fan to become grossly out of balance without showing any signs of damage?
I forgot, the housing is not rusted anywhere. Faded, but very solid with no corrosion on the bottom at all.
07-15-2005, 02:18 PM
sounds like you have a fan motor going out or bad blade....call a tech, the sooner the better...also consider a high effecient changeout
OK, I took it apart. Compressor mounts OK. There are 3 long struts connecting the top to the bottom of box. One of them loose at the top. No screw and NO SCREW HOLE in top of unit. But strut did have a hole for the screw. Some idiot at the factory never even drilled a hole for the screw, let alone put a screw in. So I match-drilled a hole and put a screw in. No more vibration. Unbelievable!
Second issue: motor has no play in the shaft sideways, but has about 1/8" axial play. Is this normal? Is the thrust bearing worn? How badly? Can the thrust bearing be replaced?
07-16-2005, 09:04 AM
1/8 end play is normal for sleeve bearings.
Thanks much, junkhound. I'm done. Frigetater, I'm sorry but loooks like the answer to your suggestions is no, no, no and no. I don't mind paying a tech a service call, even if it turns out to be a 10 minute job like this one. It's just hell getting one to come out at midnight when the outside temp is down to 90F and I can turn off the AC for a while.
Gunnery Sergeant Hartman
07-16-2005, 10:29 AM
You would have a tech come out at midnight for a vibration?
That would be one happy tech!
07-16-2005, 10:34 AM
Yellow Dot; his answer to calling a tech if you read the last thread was NO.
Dx: sorry to be so blunt, but you are an IDIOT for messing around with this unit. I guess if you smelled gas, you'd start walking around the house striking matches to find the source? Neither YOU or anyone ELSE has any business sticking their nose, fingers, and anything else in these units when they don't know what the !?*! they're doing!!
Your profile doesn't give any indication of what type of ability you have mechanical or otherwise to attempt this. SHAME on those that want to 'guide' you right into possible electrocution. Not me.
Simply stated: NO!
07-16-2005, 11:10 AM
dx,you may want to call an engineer.
I am not sure if you will be able to find a tech that is competent enough to track down your vibration problem. :rolleyes:
07-16-2005, 11:30 AM
davidr: you're just up the road from me. Do you really believe a tech couldn't diagnose and correct the problem if given the opportunity?
07-16-2005, 11:41 AM
John,check out this (http://www.hvac-talk.com/vbb/showthread.php?threadid=79591) thread.
It will explain my sarcasm,but yes I do believe a good tech could diagnose this problem.
Hey John and David, relax! Take a deep breath and read the posts before you shoot your mouths off!
Did you even notice that the problem was solved, as in done, over, The End?
Yes, a good tech could easily have solved the vibration, since I did it in 10 minutes and I'm not even an AC tech. Nobody suggested otherwise. What I did say is that I didn't want to turn off the system during the hot day, when I need cooling, so I did it at midnight. And yes, it would be silly to call a tech out at midnight for a vibration. That's why I didn't. You just made my point.
As to the unrelated and apparently more controversial subject (at least here) of who should give advice of what kind and how qualified the recipient is: If you don't like the forum rules, feel free to refrain from wasting our time. And go to the "vent your pet peeves" forum instead.
David, your sarcastic reference to the other thread is entirely appropriate here. I figured if I call 5 contractors on this vibration issue, 4 of them would tell me I need a changeout to a 55-ton, 83 SEER unit. Then of course nothing would work after the changeout and we would need to up-rate the system a bit...:)
07-16-2005, 05:26 PM
davidr: not only did i check out the thread, did you bother to read my response?
Everyone is accusing everyone else of jumping to conclusions and shooting off their mouths.
I made a statement a long time ago, that there were people that can't see the forest for the trees. I stand by that statement.
Also, did you know that if you put a frog in a cold skillet and s l o w l y bring up the heat, he will stay there 'til he's fried?
Get my point? or if not, I can reword it. I wouldn't want to 'disappoint' anyone.
If what I say here, makes someone stop and think, then fine. Just as I have learned from many on this site, I hope others are just as willing to learn.
Time to kick it up a notch!
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