I DRIVE A 2020 CHEVROLET TRAVERS AND MY WIFE DRIVES A 2022. WE LIVE IN APPLE VALLEY CA. AND THE KFI RADIO SIGNAL IS ON THE WEAK SIDE. IN THE TRAVERSE WHEN THE A/C IS ON THERE IS A BUZZ IN THE RADIO. IN THE XT5 WITH THE RADIO ON AND THE A/C ON THERE IS NO BUZZ. I KNOW IT IS CHEVY VERSES CAD, ANY IDEAS WHERE THE EXTRA FILTERING IS? RADIO OR ELECTRICAL SYSTEM?

First, just FYI, ALL CAPS is generally considered to be YELLING. I'm guessing you didn't mean to yell the whole post.

. . . a 2022 Cadillac XT5 I gather?

Which engine does it have?

I've spent a bunch of time there long ago, and listened to KFI 640 for some of it. It used to come through okay, but decades of new housing later I can imagine there are many more things attenuating the signal.

One of those things is your vehicle'* antenna. A downside to the small antennas on modern cars is that they don't receive as well as a big aerial like in the old days. This is especially true of AM radio.

Does the buzz follow the engine speed?

Is there a buzz with ignition on, radio on, and engine off?

If the Cadillac has the V-6 then they are about the same car underneath. If not then it might be a matter of different EMI environments V-6 versus 4-cylinder.

No, I did not mean to be yelling, just lazy. I use caps to make stuff stand out sometimes, but never mean to be yelling. My apologies.

Hi! Ham radio OP here, lots of experience in RF.
A/C clutch is probably generating RF noise.

You could install an RF choke on the antenna coax close to the radio.

Mike,

1. Thank You for your service.

2. Thank You for your response.

The clutch being the only thing I could think of also. Did not understand how a DC device that locks up could cause the noise. Noise does not change with engine RPM’* and no noise when the fan is running without the compressor engaged.

Taught airborne electronic equipment in the Navy, 1963 to 1967, but have no Idea what size or specification to select an RF choke. Any suggestions on what I should buy?

Thanks Again

Sorry about the yelling, have no posting educate, but willing to learn.

Thank YOU for your service! Former Army here 1996-2004

Just about any snap-over RF choke should do. But, if the noise isn't RPM based, makes me wonder if its the radio instead. Still, you could try the choke and see what happens. Otherwise, you are on a mad-hunt disconnecting devices one at a time to see what is causing it.

No worries! I figured it was something like that.

So the only time it causes the noise is when the compressor clutch is engaged?
Everything in life gives off radiation. Without using a spectrum analyzer to see what frequencies your dealing with you could use a piece of old antenna wire and use it as a filter and you can loop the wire and find where it removes that noise. Do you have any idea what I'm talking about?
It will work but it'* not practical.

I've been thinking about this. Don't these cars both have variable displacement AC compressors? I wonder if the variable displacement AC compressors have a different EMI signature. I haven't worked with them much, but don't they operate off of a PWM electrical signal of some sort?