Howdy
I don't know if this is normal, I have a 06 Megacab CTD and it runs and looks great. but when I put the AC on and I accelerate, along with the engine noise I hear a noticable groaning or moaning or droaning? Turn off the AC and no noise. Never heard this on my 99 V-10.
Is this normal?
Thank you

 

Ever hear a tractor trailer, does the same thing. It's just the fan spinning faster when you accelerate, if you pay attention it will get quieter at higher speeds. Mine does it too

 

What Frone said is correct. Our fans are electronically controlled by the ECM. They are commanding the fan to full egagement when the A/C is on to help the system work better. I kinda like the sound my self, sounds like a big rig.