are typically not electrically noisy. Where I work, we use them on some helicopters with extended instrument panels to help circulate air through the enclosure. We haven't had any problem with them interfering with the radios.
I installed a small "cyclone" avionics cooling fan this summer and no problem except for the little bit of noise it makes while running and you can hear a little whine in the audio on shut down. Worth is to keep the electrons cool