Air Conditioner Problem - Intermittent Water-like Noise

[kswpg]

Hi everyone,

I have a question about the air conditioning system and a noise it makes that started off as being quite infrequent and over the course of the summer is now happening most of the time.

First, I did search the forums. Many posts on DCCV's, but I don't think that is the problem in this case.

So this is what is happening. While the AC is on, the noise repeatably stops within seconds of disengaging the AC compressor, a noise can be heard which sounds similar to water running/building pressure inside a chamber. Its hard to explain, but its a high-pitched, "hissing" that sounds somewhat liquidy. Its a very typical noise you'd expect to hear from an air conditioning compressor, the only problem is that it is a new noise, while the AC system used to be essentially silent.

So the hissing noise beings immediately about starting the AC system, and continues until it sounds like its pressurize a chamber and then stops.

The catch is that when it began doing this, it'd make this noise for 5-10% of the time I was driving, and be silent for the rest. It progressed to making the noise as often as it wasn't, and now its probably making the noise 80-90% of the time the AC is running.

Also, the AC seems to not be as cold as it used to be. Its still cooling, but feels like it takes much longer to cool the air, but isn't blowing hot hair like many of the DCCV problems.


Any thoughts? Is this a problem any one else has encountered with the car? The auto-test for the climate control system doesn't return any codes.


Kevin

 

[kswpg]

I forgot to mention that its a 2002 LS V8.

 

[joegr]

I would suspect that you have a slow leak and your refrigerant level is getting low. The combination of the expansion valve and the variable displacement compressor can compensate for this for a while.

Also, check under the compressor and see if it is oily.

 

[kswpg]

Thanks Joe,

So do you think the noise itself is the leak, is it a noise from the system compensating from the low pressure?

The latter sounds more likely to me, as I assume a leak loud enough to be heard inside the cabin would have emptied the system extremely quickly. I don't know enough about how these types of AC's work to guess what would cause this noise if it were compensating for a low system pressure.

 

[joegr]

Thanks Joe,

So do you think the noise itself is the leak, is it a noise from the system compensating from the low pressure?

The latter sounds more likely to me, as I assume a leak loud enough to be heard inside the cabin would have emptied the system extremely quickly. I don't know enough about how these types of AC's work to guess what would cause this noise if it were compensating for a low system pressure.

Yes, the noise would be due to the low refrigerant level, not the sound of the leak itself. I suspect it is because there is liquid and gas (due to low pressure) where there is supposed to only be liquid. Of course, it could be something else.