A/C causing hum with satellite radio -- solution?

[fantoma33]

Hello. I'm new to this forum and just bought a 2007 Yaris Liftback on Saturday. So far I love it, but I'm having a problem with my satellite radio.

I installed a Sirius Stratus receiver yesterday. I'm using the audio out jack on the sirius receiver and plugging into the aux input on the factory system.

When I turn on the A/C there is a very noticeable "hum" in the background -- this only happens when the A/C is on AND i'm using the AUX input. It does NOT happen when only using the blower and AUX input, or when using the A/C and fm transmitter.

Does anyone know what could be causing this and what I can do to eliminate this annoying hum? I searched the internet and my best guess is that this could be a ground loop problem, however I'm not sure this is the actual problem since the hum does not seem to vary with RPMs.

Has anyone else experienced this? What was your solution?

Thanks for any ideas you may have. I'm not familiar with car stereo installation and am not really sure what else to try.

[edit -- hum might not be the right word to desribe the sound -- I just listened to it again an it's almost like a buzzer sound]