Whirring Noise with AC on.

[Wild Bill]

I have a 2005 base with the 3.4l V6 that I bought slightly used with 20,00 miles on it over four years ago. For the past couple of months now, I noticed that there is a 'whirring' noise under acceleration with the AC on, and it gets louder as the engine load increases (Going up hills, acellerating form a dead stop.) Also, at idle, I can hear a clanky, grinding noise when the AC is on. I am unable to hear it when I pop the hood and listen under the hood, but it is definitely heard in the cabin. Also, since this has started, I noticed that the AC takes a lot more power away form the engine than it used to, I also used to get slightly better gas mileage before it started doing this. The car has been tuned up before, the AC is refrigerant is full. Also, I am hearing an intermittent squeel form under the hood, similar to a belt squeel, but it doesn't behave like a belt squeel, being that sometimes it just stops while driving, then comes on again. This is not related to the AC, since it happens when the AC is either on or off.

[Rick]

Wild Bill wrote:

I have a 2005 base with the 3.4l V6 that I bought slightly used with 20,00 miles on it over four years ago. For the past couple of months now, I noticed that there is a 'whirring' noise under acceleration with the AC on, and it gets louder as the engine load increases (Going up hills, acellerating form a dead stop.) Also, at idle, I can hear a clanky, grinding noise when the AC is on. I am unable to hear it when I pop the hood and listen under the hood, but it is definitely heard in the cabin. Also, since this has started, I noticed that the AC takes a lot more power away form the engine than it used to, I also used to get slightly better gas mileage before it started doing this. The car has been tuned up before, the AC is refrigerant is full. Also, I am hearing an intermittent squeel form under the hood, similar to a belt squeel, but it doesn't behave like a belt squeel, being that sometimes it just stops while driving, then comes on again. This is not related to the AC, since it happens when the AC is either on or off.

I have a 2003 3.8 V-6 with the same problem. I hear a whirrling whine when the A/C is turned on. I also have a 2005 3.4 that does not have this noise.

[Wild Bill]

Any clue as to what it is?

[Technician R]

Wild Bill wrote:

I have a 2005 base with the 3.4l V6 that I bought slightly used with 20,00 miles on it over four years ago. For the past couple of months now, I noticed that there is a 'whirring' noise under acceleration with the AC on, and it gets louder as the engine load increases (Going up hills, acellerating form a dead stop.) Also, at idle, I can hear a clanky, grinding noise when the AC is on. I am unable to hear it when I pop the hood and listen under the hood, but it is definitely heard in the cabin. Also, since this has started, I noticed that the AC takes a lot more power away form the engine than it used to, I also used to get slightly better gas mileage before it started doing this. The car has been tuned up before, the AC is refrigerant is full. Also, I am hearing an intermittent squeel form under the hood, similar to a belt squeel, but it doesn't behave like a belt squeel, being that sometimes it just stops while driving, then comes on again. This is not related to the AC, since it happens when the AC is either on or off.

I have heard this complaint before from owners of 2001-2005 Impala's with the 3.8 and 3.4 engine. Some say it's the A/C compressor and some say its alternator whine. It may be the A/C compressor pulley bearing since it still does it without the A/C on. The alternator may be producing a whining noise under certain electrical load conditions. I have found that many owners forget to check their Power Steering fluid on the 3.8 engine because of the hidden location of the fill reservoir and found a low fluid level was responsible for a whining noise at all times emanating into the cabin area. The noise doesn’t seem to hurt anything with the exception of being extremely annoying to the driver.

[Technician R]

Wild Bill wrote:

I have a 2005 base with the 3.4l V6 that I bought slightly used with 20,00 miles on it over four years ago. For the past couple of months now, I noticed that there is a 'whirring' noise under acceleration with the AC on, and it gets louder as the engine load increases (Going up hills, acellerating form a dead stop.) Also, at idle, I can hear a clanky, grinding noise when the AC is on. I am unable to hear it when I pop the hood and listen under the hood, but it is definitely heard in the cabin. Also, since this has started, I noticed that the AC takes a lot more power away form the engine than it used to, I also used to get slightly better gas mileage before it started doing this. The car has been tuned up before, the AC is refrigerant is full. Also, I am hearing an intermittent squeel form under the hood, similar to a belt squeel, but it doesn't behave like a belt squeel, being that sometimes it just stops while driving, then comes on again. This is not related to the AC, since it happens when the AC is either on or off.

Some noteworthy information concerning fuel economy. Many people do not realize they are using ethanol blended fuels now. It seems like ethanol blends are all you can purchase no matter what state you live in. This will result in about 3 percent less fuel economy than you may be used to getting from your engine. Many states do not require that the ethanol blend notice be posted on the pump so you will have to ask the retailer what they are selling (if they even know or are willing to tell you). Most ethanol blends are between 6-8 percent. Some cheaper fuels will have up to 10 percent ethanol content at all times (all seasons). More expensive fuels usually run about 6 percent in the summer months and about 8 percent in the winter months. The higher the ethanol content the less fuel economy you will get. The maximum ethanol blend allowed by federal law is 10 percent (but who is checking)? It's a great way to stretch oil company profits!

[Wild Bill]

I know ny Impala is sensitive to ethanol, back in Nebraska the pumps were clearly marked with the percentage of ethanol in their fuels. Here in SC, not so much. My power steering fluid is full, I am one of the few people in my circle of friends/family that pop the hood and check the tires on Saturday mornings.

The whirring only happens with the AC on, so my first guess would be either the compressor or the clutch, unless the AC takes such an electrical load that it is the alternator, I just wanted to get other people's input too.

[Rick]

My whirring sound on the my A/C also only happens when the a/c is running. My alternator is fine and was checked under a load test. I also know the low power steering fluid noise that is in the Impala. The a/c noise is not the same noise as the low power steering fluid noise. I only hear the noise when the a/c is on and running. I also have upgraged the battery to one that has more power and cranking amps. My guess is the compressor or compressor pully may be causing the noise. I also do not have to use the a/c much because I live in a cooler climate where the a/c only has to be used maybe six times a year.

[Wild Bill]

"I live in a cooler climate where the a/c only has to be used maybe six times a year. "

Lucky you, down here I am still using the AC in NOVEMBER!

[Technician R]

Rick wrote:

My whirring sound on the my A/C also only happens when the a/c is running. My alternator is fine and was checked under a load test. I also know the low power steering fluid noise that is in the Impala. The a/c noise is not the same noise as the low power steering fluid noise. I only hear the noise when the a/c is on and running. I also have upgraged the battery to one that has more power and cranking amps. My guess is the compressor or compressor pully may be causing the noise. I also do not have to use the a/c much because I live in a cooler climate where the a/c only has to be used maybe six times a year.

An alternator can check fine under a load and output test and can still have a faulty diode allowing the alternator to become noisy at times or under specific loads. It is also important to remember that the PCM (engine computer) controls alternator output.
There may be corrosion forming somewhere in the wiring for the engine grounds or alternator or PCM grounds. I am still trying to investigate this problem. It seems to occur at any mileage or age of the vehicle. Probably another one of GM's screw ups! I forgot to mention that my 2004 Impala does this as well. My car has under 20,000 miles on it!

[Rick]

Technician R wrote:

<quoted text>An alternator can check fine under a load and output test and can still have a faulty diode allowing the alternator to become noisy at times or under specific loads. It is also important to remember that the PCM (engine computer) controls alternator output.
There may be corrosion forming somewhere in the wiring for the engine grounds or alternator or PCM grounds. I am still trying to investigate this problem. It seems to occur at any mileage or age of the vehicle. Probably another one of GM's screw ups! I forgot to mention that my 2004 Impala does this as well. My car has under 20,000 miles on it!

My 2003 Impala has 27,000 miles on it, and I purchased it brand new back in '03. GM had to replace the subframe due to premature cracks at the welds at 19,000 miles. They also replaced three rack and pinion steering shafts in the same period that kept breaking due to the faulty subframe. The subframe manufacturing defect problem has occurred in 35 percent of the Impala cars manufactured from 2000 thru 2005. Now there is also an intermittent rattling sound coming from the front left side of the dash when the car is cold and before it warms up. I have pinpointed the rattle sound coming from the instrument cluster gauge area. It looks like the instrument cluster is also going to need replacing. After giving GM three chances with car purchases, this is the last GM car I will ever buy. My first strike was on the 95 Corsica with the head gasket problem. The second chance I gave them was on the 1999 lemon Malibu purchase. The third chance they had was when I trusted them on the Impala purchase.

[Wild Bill]

Small world, I had a 95 Corsica with the LIM Gasket problem too. Let me guess, 3.1L V6?

[Rick]

I took my Impala LS to the dealer today because of a slow start problem. The batery also was not holding a charge. The dealer replaced the battery, the cables, and another battery on the identity system. The dealer also cleaned all of the connections on the battery, the ground wiring, and the alternator connections. When I got the car back, I decided to do a a/c check to see if I can still hear the whirrling sound with the a/c on. To my surprise, the noise was gone. Technician R's previous post was right on target when it came to fixing the noise in my vehicle. Check all of your wiring connections to the alternator, battery, and ground because that is what fixed my vehicle.

[Wild Bill]

Thanks a lot, Rick and Technician R. One question, what do you exactly mean by the "Battery on the identity system?"

[Rick]

Wild Bill wrote:

Thanks a lot, Rick and Technician R. One question, what do you exactly mean by the "Battery on the identity system?"

I did not know what that was either. However, when I look at my key chain, there is a chip in a device like the device you use to open and close the doors. The device states Identity on it. The identity system is a optional security system installed by the dealer at the time of vehicle purchase.

[Wild Bill]

Good to know. I know what to clean the battery connections with, but what would I use for the alternator connections and the ground connections. I guess I will hit the electrical connections to the conmpressor as well. Are there any connections to the condensor? Sorry, I regularly fix computers, not cars.