# Roof A/C Unit Vibrating



## FrankyTheHammer (Mar 7, 2012)

Hey all, this is my first time posting here, was referred here by my dad 'noquaks', looks like you all run a great community.

Anyway, looking to buy this house - it has central air, and the unit is on the roof of the house. When you turn on the A/C though you hear a severe rattling noise throughout the entire house. 

My realtor said that's normal for a rooftop unit, but I still think somethings funky. The inspector checked out the system and says it works perfectly fine...so how can I stop this annoying rattle? Is there a way to maybe add rubber feet or something like that to absorb the rattling?

I could see myself going crazy if that noise was on consistently.

Thanks!


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## hvac5646 (May 1, 2011)

give 'da inspector 'da hamma'...da-yoh


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## beenthere (Oct 11, 2008)

FrankyTheHammer said:


> Hey all, this is my first time posting here, was referred here by my dad 'noquaks', looks like you all run a great community.
> 
> Anyway, looking to buy this house - it has central air, and the unit is on the roof of the house. When you turn on the A/C though you hear a severe rattling noise throughout the entire house.
> 
> ...


Could be bad bearings in the blower, or an imbalance condenser fan blade. or something worse.

Have them get it fixed on their dime.


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## hvac5646 (May 1, 2011)

I agree. plenty of units out there and they don't vibrate. You got stiffed by the inspector who said it was ok.

make him and the real estate agent pay.


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## FrankyTheHammer (Mar 7, 2012)

haha seriously!! I'm glad I got the second and third opinions...

thanks a bunch...I'll get an air conditioning specialist to take a look and give me a quote.

why they both say its okay boggles me.


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## how (Feb 26, 2011)

Commision sales pressure. If you had just said you could live with it, folks could of moved on with your money to the next sales job. Inspecters in bed with agents receive ongoing clients, inspecters not in bed with anyone tend to reject homes because you'll end up using them again soon on the next house you choose.
A lot of conflicts of interest.


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## thermal-medics (Feb 11, 2012)

how said:


> Commision sales pressure .


 
Thats 75% of residential A/C techs in AZ. Sell at all costs....especially new units

Seriously, we have 100% commission based techs and they advertise in the big box stores for 'tune-ups'. 

Dateline usually does a number in May out here. Always entertaining especially the guy taking a xxss in the corner by the condenser - every year I xxxx you not..


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## ben's plumbing (Oct 6, 2011)

1 st get a new realtor ..2nd have them have an hvac company certify unit is in proper working order.....:yes:


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## biggles (Jan 1, 2008)

if its a bearing change out they are ducking it add a motor and thats a big bite to eat their in kahoots.....you should only hear air noise


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## noquacks (Jun 5, 2010)

Update: People, Im helping Franky, and we found out the inspector says this is very common in roof mounted units in S Cal Homes built in the 40's and 50's with units on a gable incline. Noisy ac throughout the house. He did say heavy rubber mounts could help (?). The ac is cold. 

On the real estate agent, he doesnt come across as a sleazy guy- hes goind out of his way to do so much for us (hey, he could easily choose not to), so , so far, I cant complain about his ethics- he also has seen this situatuion before- just as an agent talking/opinion- of course hes not a pro)

So, man, is this typical? Any ac guys here see this noisy situation for roof units?

Thaks again!


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## beenthere (Oct 11, 2008)

Although we don't have many, we do have some package units mounted on sloped roofs in residential settings. they aren't loud, unless something is wrong.


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## sammy37 (Dec 9, 2008)

The only unit I've ever seen that vibrated in the house, was a new Goodman heat pump and the fan blade was severly out of balance. In fact it was so bad, the plates and pictures on the walls were rattling. I replaced it and all was well.
However, its not uncommon to have a little resonating noise in the area that the unit sits under and it seems like the scrolls are worse for transfering noise than the a lot of the old recips, especially the ones that were mounted on springs.


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## Missouri Bound (Apr 9, 2011)

How old is the unit? Maybe replacing the rooftop unit should be part of the deal.


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## COLDIRON (Mar 15, 2009)

First thing I would try to stop the noise is cork and rubber equipment pads placed under the equipment.

That's only if there were no obvious vibration issues IE: bent fan blade, bent motor shaft, line sets vibrating together, fan shroud lose, compressor mounting lose or worn bushings on the compressor legs.


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## Budoy (Mar 13, 2012)

if you can hear the noise throughout the whole house ,obviously something is wrong there.Have them fixed this issue before making a deal on this house. This problem seems like mechanical problem,such as unbalanced fan blade,worn bearing.


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## spinfisher (Dec 2, 2010)

There are different levels of noise , but when it comes to vibrations.... they can only get worse. Or better yet when they completely Stop! Find out what the cause of the vibration and solve the problem, could be something loose or something getting ready to fly apart. I never trust salesman.


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## noquacks (Jun 5, 2010)

ended up that the vibration was the compressor/condenser unit had 1 or 2 bolts loose. Fixed it!! He did say that when the thing goes, better to take it down from the roof and put on the ground.

Thanks, people!


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## spinfisher (Dec 2, 2010)

Good to hear!


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## sammy37 (Dec 9, 2008)

noquacks said:


> ended up that the vibration was the compressor/condenser unit had 1 or 2 bolts loose. Fixed it!! He did say that when the thing goes, better to take it down from the roof and put on the ground.
> 
> Thanks, people!


No reason for that, rooftop setup is just fine. Just make sure the new unit is installed properly and it will last many years.


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