Loose a/c fan

wendydahle · 06-28-2016, 11:46 AM

Hi,

Wondering if anyone has ever dealt with a loose a/c fan? We are supposed to be leaving on a camping trip soon and I went out to start up the a/c before cleaning, and it was making a horrible vibrating noise.

I got the shroud off for my husband to look at when he gets to it, and I could not find anything apparent except for the fan motor seems loose. We replaced the fan blade a couple of years ago when it broke, and that cured that issue, but now it's a new problem. I am hoping we can fix this as I am trying to escape the Fourth of July fireworks in my neighborhood!!!!

Our a/c system is 17 years old and much of the parts are very rusty, including the screws holding the fan motor in place. Not sure how easy it will be to tighten them, and if tightening is even a solution to this problem. It's kind of like having a motor mount busted and there is this annoying rattle.

Anyway, I was just wondering if anyone has had this happen to them, and what did they do outside of replacing the whole a/c, which is something we will be doing probably down the road.
Thank you, Wendy Dahle, Sarasota, Florida

tjalmy · 06-28-2016, 08:28 PM

With the shroud off, run it and see where the noise comes from. In most A/C units there are two fans, the evaporator fan which sends cool air inside, and the condenser fan which casts the excess heat into the atmosphere. Neither one should be at all loose or wobbly. It may be a mounting bracket on the fan housing, or a bad bearing on the fan motor. Does the motor itself wobble? Is there a lot of play in the fan shaft? Observe it while running, check for loose parts while power is disconnected!
I hope this helps.
Tom

wendydahle · 06-29-2016, 08:26 AM

Thank you for responding. It seems the fan motor is loose. We have the shroud off and are trying to figure out why it is loose.

Thankfully when we had the fan motor problems before, and it turned out to be a broken fan blade, another person (John B perhaps?) on this site posted photos of how to replace the fan motor, which we may have to do now.

We had plans to camp this weekend, but only if we can get this fixed. Not sure what we will find as we get further into it.

Thank you for your assistance!

**JohnB** · 06-29-2016, 06:31 PM

Hi Wendy,

I do not know the model of AC unit that is on your 99 Sunline. But this may be close.

First, if the fan unit, motor or blades are loose, do not run it in this condition trying to cool the camper down. If the fan blade wobbles bad enough and hits your evaporator or condenser coil, they can make a big mess quick.

If the actual motor mounting is loose, h'mm OK that should not be, but that doe not mean it is not.

See if this helps.

On the 2004 era units there are rubber vibration mounts to isolate the motor from the fan housing for anti vibration purposes. Those rubber mounts use a small tube or sleeve inside the. When you tighten up the screws, they are supposed bottom out on the sleeves so the bolt will be tight and not come loose but yet the rubber can still have a level of freedom to move and not transmit vibration to the fan housing. This is a somewhat standard shock mounting type of system.

See these 2 pics.

The sleeves

And the nuts on the studs over the sleeves

If those sleeves are for some reason missing, that can be part of or all of the problem. You cannot tighten up the motor to stay tight trying to tighten against the rubber shock mount. The nut needs to bottom out solid against the sleeve and washer if there is one to stay tight. Each nut should have a flat washer and a lock washer.

So check if the sleeves are in there. A lock washer should also be with each nut to help with anti back off of the nut.

There is also a possibility the rubber mounts may be decayed and starting to fall apart. The rubber is deteriorating. You can see this by eye with good lighting, looks for lots of cracks and black dust or crumbs under the motor of falling rubber parts.

Hope this helps

John

wendydahle · 06-29-2016, 07:40 PM

Thank you John! That is perfect! Just what we needed to know! The photos are perfect! Makes looking at things a little easier. Nice to see how it should be. Things are so rusted they don't quite look the same.

So we have it all apart now, and are trying to assess what exactly is going on! Seems the motor is a little loose and the bolts holding it seem to be a little loose as well. Hopefully we can find the source of the awful vibration.

Also had to clean a ton of those mud wasp nests out of there again. When the camper sits, even for a few weeks, they make nests any place out of the rain.

I appreciate your quick response. We are trying to get away for the weekend as our dogs don't deal well with the neighborhood fireworks, and we go to a campground that is surrounded by trees and a big lake. Things are pretty quiet and we can all get some rest this weekend!

Thank you!

wendydahle · 06-30-2016, 06:59 AM

I feel like such an idiot . . . turns out our fan motor problem was due to a mud wasp nest on the inside of the fan blade. We couldn't see it until we had some of the unit apart and had more light. It was in a really hidden spot and was just heavy enough it was throwing the fan out of balance making the hideous vibration noise.

While we had it open, we cleaned it all out. Problem solved! Works good again, until at some point we will have to change the fan motor because it still does have some issues that for sure will cause us problems down the road.

But for now, we are camping this weekend! Yippee!!!!

**JohnB** · 06-30-2016, 03:10 PM

That is great news!!! and simple!!!

Having to actually take the motor out of the AC unit is, involved.... They way they are made, both the evaporator and the condenser could and the compressor have to come out as a unit so you can get the fan blade off the inside evaporator side. Basically there is not much left...

Have a good camping weekend