Embarrassing A/C noises

Post by **IVIUSTANG** » 13 Jul 2010, 00:54

Hey gang,

For the three years I have owned my beloved S70 the air conditioning has randomly made very loud squealing like it was releasing pressure or something from a valve. I have never been 100% happy with how my car idles with the A/C on, when it is not screaming at high pitch it is making tiny little noises that I can't really describe.

What is happening with the high pitched squeal and how do I remedy it, I have never seen any other car do this. A/C works great apart from the occasional racket described.

Thanks,

- Jesse

Post by **igel513** » 13 Jul 2010, 01:01

Possible causes could be bad alternator bearing, hardened drive belts. Those components can cause those squealling sound. Also check the slack on those drive belts, if they're too tight or no slack, the belts could squeal.

xjflexer · Post by **xjflexer** » 13 Jul 2010, 05:43

I would say that if this noise only happens with the A/C on, it could quite possibly be a bad bearing in the compressor. BUT, the is a possibility that your belt is old and loose, and the extra strain from the compressor being on can cause some slippage if the belt cannot keep the compressor spinning at speed with all of the other accessories it's driving. Those are the first things I would look at.

Post by **jblackburn** » 13 Jul 2010, 07:19

Or its a bad orifice tube. See if you can pinpoint where the noise is coming from.

Post by **IVIUSTANG** » 13 Jul 2010, 12:20

It isn't the belt I changed that and checked the tensioner before I went on my trip; it simply doesn't sound like a belt either. What is this orifice tube you speak of?

It kind of sounds like high pitched feedback from a microphone. It starts out high and then gets quieter and quieter until it fades away.

- Jesse

Post by **jblackburn** » 13 Jul 2010, 12:34

And it would make exactly that noise you describe!

The highlighted part right here, "expansion valve" is also called the orifice tube.

It's right in front of the receiver/dryer. The part itself is cheap and easy to fix, unfortunately the whole AC system has to be evacuated & recharged to do it.

Post by **IVIUSTANG** » 13 Jul 2010, 12:38

Thanks, I'll give that a look this afternoon; how is it diagnosed?

- Jesse

Post by **jblackburn** » 13 Jul 2010, 12:41

Mainly just the noise it makes. If your AC lets out a squeal after the car is shut off, or while it is charging up for the first time in the mornings, that's what causes it as the pressure in the system is equalizing. There is another one in this AC system somewhere, but I can't tell from the diagram where it is. Listen near the dryer (the metal canister at the front, right side of the engine) and see if you can pinpoint the noise to that area.

MaxIcon · Post by **MaxIcon** » 13 Jul 2010, 13:27

My 99 C70 does this too. It's a high-pitched whine that builds and drifts away when the AC is running. It usually makes its last gasp a short time after the engine's shut off. It's definitely annoying and potentially embarassing!

The mechanic said it was the expansion valve. At the time, I was unemployed, and since everything was working fine (air blowing cold), we left it. As jablackburn says, it's an easy fix, except for the evacuation/recharge part.

Post by **IVIUSTANG** » 13 Jul 2010, 14:51

Perfect, I will replace it!

- Jesse