2008 Tacoma rattle while in idle w/ AC on

ok, i have noticed a rattle in my 2008 when i am in a drive thru or just parked with the AC on. It sounds like the rattling is coming from underneath the truck on the driver’s side. Any sugguestions on what it might be?

 

Something may be loose like a metal bracket. Had a similar problem when idling in P with A/C on, but I was experiencing an oscillating sound; not a rattle.
If your problem occurs only with gear selector in D, you'll need to have a volunteer sit behind the wheel with their foot on the brake while you crawl around under the hood and down underneath.

 

it is only when in park and the engine is running with AC on

 

3 things.

1) Check you exhaust connections for broken clamps. They are cheap, thin, low quality metal.
2) Check your belt tensioner arm. It wears out. Get under the truck and watch the A/C compressor. If the clutch engages and the pulley spins and the sound appears and disappears with that action, it could be chattering from the arm.
3) You got gremlins under the hood.

 

Check the heat shield on on the catalytic converter.

 

I also have a 2008 and hearing the same noise. I really hear it the best between 30-40 mph and then it disappears.
I think its from the catalytic converter under the drivers side floor board. There are four catalytic converters on the 4.0L. The one that I think is bad is the most costly, $254 aftermarket.

 

After getting underneath to take a good look for the rattle sound I found both bolts that attach the heat shield on the converter rusted and one completely gone. Replaced bolts, no more rattle.