Rattle/Ratchet noise in Engine Compartment

Ok Friends, this is a strange one!

I own a 2009 Tacoma Pre-Runner 6 cylinder and there is a rattling/ratcheting noise coming from the engine. It only happens when the A/C cycles on and off. I replaced the compressor and clutch, thinking that was the problem but still have noise. Again, it only happens when the A/C engages and the A/C clutch kicks into operation! Obviously, the load on the components relying on the drive belt for operation has something to do with this noise. I had the water pump replaced at 110K miles (now 150K) but alternator/generator, tensioner pully and fan clutch all unreplaced and suspect. Again, only happens when A/C clutch engages.
Any Thoughts??
Thanks, Mudbug

 

I'd remove the belt and inspect all the pulleys.

 

I'd check the pulleys first as @TnShooter suggested and then make sure none of the AC hard lines are contacting anything.

 

Appreciate your response but I already have inspected the pulleys when I replaced the A/C compressor and they seem to be OK. The noise is only when the A/C clutch kicks in and the compressor is in operation, that is why I replaced it but the noise is still there. I am stumped but will replace the fan clutch and tensioner to see if noise goes away. Thanks.

 

How did you inspect the pulleys? You don't just spin them. You grab them and move them left to right and fore-aft. There should be no play. Have someone turn the AC on while you view the belt and pulleys to see if you spot any obvious issues. If the belt is shaking too much, you may need a new belt tensioner.

 

I had a similar noise except it would happen after I put it in drive as well. It was my tensioner flopping around. It was really easy to see when I pulled skid plate and took a look. It was a PITA to replace tho. I dented an AC line pretty good too lmao (still works so don’t care). Btw, it’s easier to pull the plastic flap from left front wheel well and take your alternator out there as well as most of your bolts to AC and tensioner.