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-   -   Noise above 35 MPH with A/C on (http://www.peachparts.com/shopforum/diesel-discussion/214052-noise-above-35-mph-c.html)

zeke 02-18-2008 11:13 AM
Noise above 35 MPH with A/C on
 
This is in the 240D (manual CC)

It sounds like a pigeon, and seems to be coming from behind the instrument cluster.
Like a whining gurgle? Kind of rhythmic, or maybe cyclic.

When I turn the compressor off it goes away.

Doesn't vary if I turn the compressor control knob up or down - if it is on, it makes the sound.

The speedo seems to dip slightly with each pigeon "coo".

A/C seems to be working, though maybe not quite as well. (It has been converted to 134a, so it isn't ever a freezer.

What should I look for?

tangofox007 02-18-2008 11:51 AM
Quote:
Originally Posted by zeke (Post 1767211)
Doesn't vary if I turn the compressor control knob up or down - if it is on, it makes the sound.
The compressor speed is a function on engine rpm only. I suspect that your "compressor control knob" is actually controlling something else.

zeke 02-18-2008 01:26 PM
Quote:
Originally Posted by tangofox007 (Post 1767250)
The compressor speed is a function on engine rpm only. I suspect that your "compressor control knob" is actually controlling something else.
It must control the size of the opening that allows cooled air in. The higher I turn it, the colder it gets.

The noise doesn't vary with RPM, only speed.

If I open the throttle in neutral, the sound doesn't occur.

Also, shifting gears (thus changing RPM but holding speed) doesn't change the sound.

If I shift into neutral and then stop the car, the sound fades away somewhere around 35 mph.

RichardLSU 02-18-2008 10:01 PM
My car kind of makes a whining noise when I have my heater/fan on. If i hit the gas or slow down it goes away but when i settle into another "groove" it will come back on. If i turn off my climate control it goes away completely. I figure its gremlins. :D

TylerH860 02-18-2008 10:27 PM
Quote:
Originally Posted by RichardLSU (Post 1767674)
My car kind of makes a whining noise when I have my heater/fan on. If i hit the gas or slow down it goes away but when i settle into another "groove" it will come back on. If i turn off my climate control it goes away completely. I figure its gremlins. :D

Gremlins indeed. I get a little flutter, like pigeons or squirrels hiding in there, with the AC on my SL. Intermittent, barely audible, nothing light background music doesn't drown out.

I'm not concerned, yet! Surely someone will post something that will scare the S*** out of me pertaining to this issue.

TylerH860 02-18-2008 10:29 PM
Quote:
Originally Posted by zeke (Post 1767211)
This is in the 240D (manual CC)

It sounds like a pigeon, and seems to be coming from behind the instrument cluster.
Like a whining gurgle? Kind of rhythmic, or maybe cyclic.

When I turn the compressor off it goes away.

Doesn't vary if I turn the compressor control knob up or down - if it is on, it makes the sound.

The speedo seems to dip slightly with each pigeon "coo".

A/C seems to be working, though maybe not quite as well. (It has been converted to 134a, so it isn't ever a freezer.

What should I look for?

Could be a case of jealousy. Are you dividing your time evenly between your 240d and 'new' 300td?:D

zeke 02-18-2008 10:44 PM
Quote:
Originally Posted by TylerH860 (Post 1767700)
Could be a case of jealousy. Are you dividing your time evenly between your 240d and 'new' 300td?:D
nah....she knows she will always be my first
:love:

Seriously, though-could it be due to low pressure?

It seems to be cooling worse than usual - at least I know others have the same sort of noise - though I would need to put it on the metal station to drown mine out.

No noise on the way home tonight, BTW.....:confused:

TylerH860 02-18-2008 10:45 PM
Is it leaking?

zeke 02-19-2008 08:44 AM
I'm not sure.....I have to get a gauge.

It has never cooled very well, but seems to be worse now.


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