Whistling sound when taking foot off accelerator

drckarcher · Postby **drckarcher** » Sat Dec 08, 2018 10:45 am

Hi,

my 2002 Mk2.5 is making a short, loud, high pitched whistling sound when rapidly taking the foot off the accelerator.

It only occurs at higher revs, is independent of whether or not the clutch pedal is depressed and it only occurs when the aircon is on at the time.

Any ideas?

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manga_blue · Postby **manga_blue** » Sat Dec 08, 2018 2:30 pm

Slipping aircon drive belt?

hks_kansei · Postby **hks_kansei** » Sat Dec 08, 2018 4:22 pm

I'd suggest aircon belt.
Otherwise, one of the bearings in the pulleys etc related to the aircon.

Mine has a weird whistly noise during revs, but that's just a floppy bearing in one of the idler pulleys.

Custardtart · Postby **Custardtart** » Sun Dec 09, 2018 5:53 pm

Someone snuck into your garage and fitted a turbo?

drckarcher · Postby **drckarcher** » Thu Dec 20, 2018 9:16 am

Aircon belts checked- all okay. Not worm our, good tension.
Still not sure what this could be.

The weird thing is that it only happens at high revs >5000/min

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bruce · Postby **bruce** » Thu Dec 20, 2018 1:15 pm

Maybe the other belt is worn? As said, maybe aircon bearings.
It's unlikely we're gonna solve this one.

Aiming Faster · Postby **Aiming Faster** » Sat Jan 05, 2019 7:23 pm

Some ECUs switch off the A/C compressor under heavy acceleration (saves power loss to compressor), as you back off from a rev, ECU turns it back on. It may be the magnetic clutch grabbing which causes the belt or clutch to make the noise??