Dometic AC problem

[TravelinCircus]

Wondering if anyone has had this issue with a Dometic AC.
We have a 2015 Cyclone 4200.
When the Ac compressor starts up there is a loud buzzing noise that can be heard inside and outside (From about a block away!) of the coach.
My thought was a bad relay in the controls, but after getting a new relay control unit and installing it, the same issue is happening.
Is there anything in the compressor that could be buzzing? Possibly not wired correctly from the factory?
My wife and I live in the coach full time during my construction projects and unfortunately we are not close to any service centers or and RV repair techs that can check the unit without substantial cost.
Any suggestions?

 

[justafordguy]

Does it still cool?

I just had one of my 3 month old Dometic A/C units replaced yesterday under warranty. It would run but not cool, lost all the freon somehow.

 

[TravelinCircus]

Yes it still cools, but it is sooo loud you can't talk over it.

 

[Silverado23]

Is one of the fans rubbing the shroud or a tag/label on any of the wires interfering with the fan?

 

[BlackT]

The same thing happened to one of our air conditioners. I removed the cover on the roof and found that a copper tube was vibrating against a portion of the a.c. frame when the compressor started. I bent the tube slightly with my hands to gain some clearance. Problem solved.

 

[TravelinCircus]

No. When the unit first comes on the fan runs and the units sounds normal.
When the compressor cycles on, thats when the loud buzzing noise starts.

 

[TravelinCircus]

Thanks for that BlackT. I will try that when I get home.
That's the kind of easy fix I like!

 

[57chevyconvt]

Agree with BlackT as to probable source of noise. Check the compressor hold down bolts and rubber bushings as a potential source of vibration. Naturally you will need to make these checks with the cover removed and unit in operation.