BRZ AC Rattle?
 

New to the forums!

I found some stuff that were related to my issue when I used the "Search" feature.

But most of them described a chirp or flapping noise.


This is a definite rattle noise. only happens with the AC on.

https://youtu.be/QsBL4mFIfcc


Any help is appreciated.

Hi Xman17 and welcome to posting to the forum......:clap:

What engine mods do you have ..??

Does it sound like the sound is coming from the compressor ..??

So, it doesn't make the sound if the compressor clutch is NOT engaged .. ??

Is the system cooling OK ..??

Come back.


humfrz

Greddy Turbo on E85 with a Tune from Evasive.

It sounds like it's coming from the vibration of the pulley in the video.

Cooling system is fine. Yeah there is no sound when AC is off.

OK. The idler pulley does look like it's working a little harder, but that would be expected because the locked up compressor is putting more stress on the belt.

However, the idler pulley could be bad. If you loosen it up, does it spin free and doesn't wobble ..??

Can you get rod to touch the compressor (with your ear next to the other end) to see of the sound is coming from the locked compressor .. ??

Have you checked to make sure the compressor is bolted on tight ..??

It could be that the clutch on the compressor is damaged and making the compressor unit rattle when it engages.

I'll ring up ol @Ultramaroon ...... for an opinion.....he has good ears .....;)

Stay tuned.


humfrz

Here's something interesting. The rattle goes away when the clutch is pressed in? That's so weird.

Do you mean the driveline clutch or the clutch on the compressor ..??


humfrz

Drive line clutch, but actually it might not be it. Might just be my imagination. Though the one thing that does trigger it is the AC.

I think it might have something to do with the idler pulley?

If it had something to do with the driveline clutch ...... that is a whole new can of TOB worms.

If you suspect the idler pulley, I'd suggest you loosen the belt and see if the pulley spins freely and doesn't wobble on the shaft.

@Ultramaroon is LATE to this party ..... :sigh:


humfrz

It's just the gearbox. All the gears rotate whenever the input shaft spins. When the engine spins slowly, the firing pulses cause the gears to rattle a little.

The AC increases the load on the engine at idle so you get more of the rattle.

Normal.

Keep your pantyhose on. Mrs. Ultra and I were enjoying a relaxing evening watching West Wing reruns. Took me a while to get to the clip.

And when you press the clutch all the way down the noise disappears?

Yup. Ever heard it? It's more obvious when it's really cold.

Nop, bloody hot (+85 °F) it disappear if press down the clutch or turning off the AC. Glad its just another quirk

Thanks for all the responses guys. Still getting used to the small quirks of the car.

Reminds me of my MR2 where I used to hear all the clicks, clunks, and squeeks of it all around.