Navigation Installation Problems

[Editorchops]

Yesterday, I had my navigation installed by Al&Ed's out here in Los Angeles, but now I'm having a few issues. I'm noticing a buzz in my speakers that raises with my engine RPM. Also, my A/C is blowing only hot air out of the vents. Has anyone had these same issues with the Nav install? I'm taking my car back to the shop this weekend, but I'd like to be armed with some information for these guys. Any help would be appreciated.

Thanks,

Editorchops