Squealing/Rattle under vehicle when AC is on

[SlvrRnnR]

Has anyone experienced this?

In drive with brake pressed down, turn on AC and it starts. Turn off AC it stops. When driving no noise and AC is working.
Serpentine belt looks good, an idler pulley maybe? AC compressor clutch also came up in my research.

- YouTube

 

[Bmnorm2]

Has anyone experienced this?

In drive with brake pressed down, turn on AC and it starts. Turn off AC it stops. When driving no noise and AC is working.
Serpentine belt looks good, an idler pulley maybe? AC compressor clutch also came up in my research.

- YouTube

Definitely either belt, one of the pulley bearings, or the tensioner. Do some isolation type trouble shooting within those components and system.

 

[johnnygraphic]

Definitely either belt, one of the pulley bearings, or the tensioner. Do some isolation type trouble shooting within those components and system.

Have you tried to switch the AC compressor on/off with the fan still running?

You don't say year or mileage of your 4Runner. I have have the same issue with my AC on my 2004 BMW 330i with 156k miles. It's been this way for quite a while now. I used my meat thermometer (Thermapen) and checked the temp and it's a chilly 44 degrees so it seems to be working just fine. Might need to get it recharged? I just took it to my mechanic and he checked out the compressor and said everything seems to be working fine and that it might be the tensioner pulley that is squeaking. When you turn the AC compressor on, it can put more tension on the tensioner and will cause more noise at times. One nice thing is that the BMW engine has a separate belt and tensioner for just the AC, so that makes it tons easier than the Toyota which looks like it's one giant belt with several pulleys and tensioners.

The tensioner is a relatively cheap and easy item to replace DIY.

 

[SlvrRnnR]

Have you tried to switch the AC compressor on/off with the fan still running?

You don't say year or mileage of your 4Runner. I have have the same issue with my AC on my 2004 BMW 330i with 156k miles. It's been this way for quite a while now. I used my meat thermometer (Thermapen) and checked the temp and it's a chilly 44 degrees so it seems to be working just fine. Might need to get it recharged? I just took it to my mechanic and he checked out the compressor and said everything seems to be working fine and that it might be the tensioner pulley that is squeaking. When you turn the AC compressor on, it can put more tension on the tensioner and will cause more noise at times. One nice thing is that the BMW engine has a separate belt and tensioner for just the AC, so that makes it tons easier than the Toyota which looks like it's one giant belt with several pulleys and tensioners.

The tensioner is a relatively cheap and easy item to replace DIY.

2018 with 60K miles. Well technically 59K to be exact, and I was already
planning on changing the serpentine belt and idler pulleys (No 1 & 2's) this fall.
Belt still looks decent though, I did notice the Idler No 2 next to the alternator is corroded and has a bit of play (wobble) to it where the others don't have any play at all. If I think about when its happened it was on extremely hot days, when the AC was on.Only in drive with the brake on though. Still getting good cold air cycling through. The last two days I've tried to replicate and get the sound to come back but it hasn't. Hoping it's something simple, I'll have to look up how to replace the tensioner, I know it's comes as a unit, the pulley doesnt come separately.