I have a 2003 civic with 39000 miles and i have noticed that when i turn on the ac and drive with it on my car makes this loud grumbling noise underneath the hood and i can feel the vibration under my brake pedal. The noise usually occurs when i have taken the car into fifth gear then had to slow back down. although it does occur at slow speeds also. The noise is reoccuring and does not last long, maybe 5-15 seconds each time. I took it to the Honda dealer twice and they dont know what is causing the noise. I recently had 1st and 2nd gear redone (honda stated it was bad from the factory) then I had to get a tranny overhaul because the honda dealer claimed they put it back together wrong the first time and placed the engine mount block in wrong. any ideas on what might be causing the grumbling noise?