Noisy Air Conditioner

[Larry71]

I recently had a new air conditioner installed in my 1971 Safari. It worked fine on our last trip in May. The rig is parked now but when I turned on the AC while cleaning inside I got loud shuddering vibrations when I turned it on high. When I lowered it to low speed it quited down some but it still creates rattles in things stored in the closets. It makes the same sounds if I only turn the fan on. I can't find any loose connections from inside the rig. I have not taken off the shroud to check for loose fittings on the roof. Any ideas what could cause this shuddring in the AC unit? If it's something simple I will try to fix it myself but if it is a faulty installation I will have to take it back to the repair shop.

[lewster]

Larry,

It sounds like you have a balance problem on your blower motor. You didn't specify what type of A/C you have, but most rotary cage blowers are similar. You should unplug the trailer or switch off the A/C breaker, get on your roof, remove that A/C shroud and look in the central section of the unit where the blower motor connects to the frame. There are 4 bolts that attach the mounting plates to the frame, and 4 very long horizontal bolts that attach the motor to the plates. Tighten ALL. Then rotate the blower cage with your hand while holding the shaft to see if there is any play in the bolt that locks the cage to the motor shaft. Tighten as necessary.

That should solve your problem. If not, we have to dig a little deeper .

[Larry71]

Hi Lew,

Thanks for your response. I took off the shroud and tightened all the bolts. I turned on the fan again and it still rattled. I was on the roof and checked the unit while it was running. The fan is wobbling and causing all the vibration. What I think is the condenser coil is not moving at all.

The A/C unit is A Duo-Therm by Dometic, Model 57915.331. I checked the limited manual they supplied but there are no troubleshooting hints.

Any other thoughts?

Larry