Air conditioner vibrating thru the ceiling

bigdob24 · Apr 7, 2021

I have a 2018 BC 3560SS and lately the bedroom air has a bad vibration.
I have removed the fresh air vent covers and pressed around there with no results and also held a rod thru the air vents and no vibration there either.
‘So it has to be in or under the air unit.
Maybe someone has had this problem and can give some advise before I remove the cover .
Thanks
BD

cookie · Apr 7, 2021

It seems that when there is an annoying vibration it's a sign that the fan is out of balance.
Could be caused by an insect nest on one of the blades.
I suggest pulling the cover off and inspecting the fan blades along with everything else up there.

Peace
Dave

bigdob24 · Apr 7, 2021

I’ll have a look
Thanks

danemayer · Apr 7, 2021

When getting ready to remove the cover, assume a hornet nest is waiting for you. It might not be there, but you don't want to jump back and fall off the roof.

Flick · Apr 7, 2021

cookie said:
It seems that when there is an annoying vibration it's a sign that the fan is out of balance.
Could be caused by an insect nest on one of the blades.
I suggest pulling the cover off and inspecting the fan blades along with everything else up there.

Peace
Dave

Exactly what it is. Get the water hose out and give it a bath.

centerline · Apr 7, 2021

hopefully it is only a piece of debris that has fallen into the fan and causing it to be out of balance... but if the circuit isnt allowing enough power thru to allow the motor to get out of start up mode, it will vibrate and rumble like crazy until you shut it off.... in addition, this condition would be extremely harmful to the AC unit

wdk450 · Apr 8, 2021

You might also make sure that the 4 corner mounting bolts are snug (not overly tight, though).

https://rvlife.com/air-conditioner-bolts/#:~:text=You'll need to check,correctly keeps the water out.

bigdob24 · Apr 8, 2021

Flick said:
Exactly what it is. Get the water hose out and give it a bath.

After turning off the power, how do you go about safely giving your air conditioner a bath?

Flick · Apr 8, 2021

bigdob24 said:
After turning off the power, how do you go about safely giving your air conditioner a bath?

It’s pretty simple. With the power off as you said, go up on the roof and remove the ac cover or shroud. There will be 4 screws holding it on. The likely culprit is a mud dauber that has built a mud nest on one of the blades. Look close. The mud could be on the back side of the blade. If you turn the fan by hand, the nest will usually carry the mud nest to the bottom. Then take a water hose and rinse the entire ac unit to wash away the mud. Try not to get to much water into the electric components, but it won’t hurt if some gets in there. Also wash out the condenser.

Some water may drip down into the inside, so if it’s over a bed, protect the area with a towel or two.

centerline · Apr 8, 2021

Flick said:
It’s pretty simple. With the power off as you said, go up on the roof and remove the ac cover or shroud. There will be 4 screws holding it on. The likely culprit is a mud dauber that has built a mud nest on one of the blades. Look close. The mud could be on the back side of the blade. If you turn the fan by hand, the nest will usually carry the mud nest to the bottom. Then take a water hose and rinse the entire ac unit to wash away the mud. Try not to get to much water into the electric components, but it won’t hurt if some gets in there. Also wash out the condenser.

Some water may drip down into the inside, so if it’s over a bed, protect the area with a towel or two.

additionally, be very careful about spraying the cooling fins with the water hose, as the pressure may bend them over, preventing any cooling effect in that spot. and its a real pain using a toothpick to straighten them out again... if you dont have a fin straightener tool.

bigdob24 · Apr 15, 2021

Of coarse it can’t be simple
I took it apart and all the fins and blades are in good shape and all was tight.
‘Found a bunch of wires and cables that were down on top of the ceiling and thought that if I tied them up it would solve the vibration.
Wrapped them up and put it all back and started it up and it still vibrates, will take it all apart when I get home and look under the air into the vents and see if there is something there.
‘Thanks for the advise.
BD

Dahillbilly · Apr 15, 2021

some of those fans have a little weight clipped onto a blade for balancing, if that weight comes off it will rattle & vibrate like crazy.

wdk450 · Apr 16, 2021

2 sources of vibration in RV rooftop air conditioners are the fans (actually 2 fan squirrel cage blowers on a common shaft from the same motor), and the cooling compressor. If you run the ac unit on "Fan" only (no cooling)and have the vibration problem, then the vibration is coming from the fans assembly. If the vibration only comes when you are cooling, then the vibration is coming from the compressor. Rule out the fan assembly by swapping out all 3 components - blower fan, motor, evaporator fan; if that doesn't reduce the vibration then it's probably the compressor. As AC units get older compressors can get noisier. Replacing the entire upper unit makes more economic sense than trying to fix the freon cooling system.

michaljhon · Aug 12, 2021

Air conditioner's fan should be out of balanced. If fan is not out of balance there will be problem with cooling compressor. Whenever gas level decrease in compressor it may cause of vibration. These are the two common problem of Vibration.

Air conditioner vibrating thru the ceiling

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