I've installed a CB radio (an old Cobra 19 from my dad's trucking days) with a roof-mount magnetic antenna (for now). The problem I'm having is that the CB works fine with the A/C blower off, but when I turn on the air/blower, I get a high pitched whine in the CB speaker (which gets higher as I increase blower speed). I've tried simply connecting the CB directly to the battery and still get the same issue. Has anyone had this problem or do any of you have any idea how to solve it?

I did order a Noise Filter but unfortunately it came with a short in it and just starts smoking as soon as its plugged in Guess I've gotta return that.

Thanks in advance!

 

It sounds like you've got a bad ground on either the A/C or on the CB Radio.

I'd poke around around under the hood and check your main grounds. In many cases, adding a few additional cables from individual components directly to the chassis will help clear up the noise pollution you're getting.

 

pretty common interference with any CB

I think a lot of people will say its a bad ground... I've heard this on every CB I've seen in any truck

including my own... a built in noise reducer in my CB cuts it down a lot and my stuff is grounded to the truck pretty damn well.

 

i think its important to re-mention you said you hooked it straight to the battery...

not sure you can much more grounded than that =D

 

Exactly... that's why I am thinking that it has to be the grounding on the AC blower. In my check on the AC grounding... what should I be looking for? Corrosion, frayed wires?

 

Blower is a "motor" (doh).
Perhaps its putting out AM noize from the magnetic fields it generates to spin the armature.

Get a rewound blower motor (new brushes)?

Use a cheap AM transistor radio and see if the blower motor puts out AM noize

 

You could try running it thru a ground loop isolator to get rid of the hum.

 

Run your wires so they are not near or close to the A/C wires. Any devices that emit sound can be manipulated by other device's power wires. This is a common problem in car audio as well. When you setup an amplifier in a car you run the power cable on one side of the vehicle, and the audio cables on the other. This will prevent any wire interference.

 

I get EFI interference with my cb. Twisting the hot and ground of teh cb all the way to the Batt helped to reject noise a little bit. I also ran the coax under the carpet down the center of my truck (The wiring is all in the sides as far as I could see. I still have some noise, but it is much more bearable now.