Whine from engine when AC is engaged

[Agent WD-40]

Does anybody have a whine coming from the engine compartment when the AC is engaged? My truck never used to do this. It almost sounds like the belt is loose. Is there a simple fix for this problem or do I need to make another trip to the dealer?

[SATundra]

Define "whine", a loose belt should "squeal" not whine.

[Stooge]

It also could be "throttling noise" of the refrigerant flashing through the expansion valve. Mine used to do this and I thought it was a belt or compressor "whine." Add a touch of refrigerant (R-134A). This will increase the pressure in the system slightly and stop the "throttling noise." Alternatively, take it back to the dealer, have them dump the charge, evacuate the system and recharge the system using the manufacturer's specs. using a "charging bottle." This will ensure that the exact amount of refrigerant (charge) is in the system and will stop the noise.

[KLS]

Originally posted by Stooge
It also could be "throttling noise" of the refrigerant flashing through the expansion valve. Mine used to do this and I thought it was a belt or compressor "whine." Add a touch of refrigerant (R-134A). This will increase the pressure in the system slightly and stop the "throttling noise." Alternatively, take it back to the dealer, have them dump the charge, evacuate the system and recharge the system using the manufacturer's specs. using a "charging bottle." This will ensure that the exact amount of refrigerant (charge) is in the system and will stop the noise.

What you describe sounds like an inadequate charge of refrigerant. When the system is running you can look into the sight glass on the top of the receiver (the vertical aluminum cylinder in front of the radiator). If you see bubbles, the charge is low. Either some of the refrigerant charge has leaked out or it was low to start with. Yes, the correct way is to remove the existing charge, find and fix the leak, and add the correct weight of refrigerant. The simple way is to add just enough additional R134a until you no longer see bubbles. If there is a good charge, the sight glass will look empty! Liquid refrigerant is water-clear. An actual empty system would show a bit of foggy vapor in the sight glass.

Ken

[cwags]

I've had the same problem. I first noticed that my fan belt would squeel when I would start the truck in the morning, but it would go away and would not squeel again for the rest of the day. Then I noticed a squeel when I was driving, but only when the a/c would kick in. I thought that the problem was the fan belt. I took my truck to the dealer and they changed the belt tensioner. Since then I haven't had the belt squeel in the morning, but I still have the noise when driving. I don't think the noise I hear when driving is the belt because when I roll down the window I can't hear it. I have looked at the window on the top of the cylinder in front of the radiator when my truck is running and I don't see any bubbles or fog. Is there something else that could be causing this noise? Most people don't notice it until I point it out, but it annoys the hell out of me. I appreciate any help.
Thanks,

Chris

2001 SR5 4.7L V8

[Agent WD-40]

I looked in my little window, no fog or bubbles. I am going to take it into the dealer. The noise kind of sounds like when you turn the steering wheel too much and it wont move any more. Then you get that noise from the power steering pump. It is not quite that loud though.

[Stooge]

Again, all of this seems to be noise through the expansion valve. Note that there is probably nothing at all wrong, except that the design of the expansion valve allows throttling noise to be evident. If your air conditioner is working well, I would resist having it "checked by the dealer," unless he agrees to evacuate the entire system, using a vaccum pump, and then recharging the system with the proper amount of oil and refrigerant with a charging bottle. Many times this process is done incorrectly, and introduces air into the system if not done correctly. In addition, loss of compressor oil will shorten the life of the compressor.

[v8Toilet]

Mine does it too!

[Agent WD-40]

I am going to just leave it. This time it might just really be something that "they all do".

[breakmark]

No, they shouldn't all do it. I run my AC nearly full-time in the summer in Phoenix, AZ and it doesn't whine. I don't know if the dealer would do the work for free/cheap but it should be fixable, imho.

[JeffD]

I have fairly loud alternator whine now, apparently it is something that toyota's do when they get miles on them. I have friends with camry's, tundra's, and tacomas and they all do it now. Mine is silent unless the A/C is on, or the headlights, or both together. It is loudest first thing in the morning (recharging lost battery capacity from sitting?), but is always audible at idle. I have just about 100k. it was silent when new, but it still works fine.

[Mxlion11]

I have heard this sound (whine/roar) when the AC is on since i drove it home. And it is only 3 months old! I asked the dealer about it and they said that is was 'normal' but the more i use it the more i realize how loud it is compared with other cars. Like my wife's Altima has no difference in sound (from the inside) when the AC is off or on. I really find it annoying that toyota would allow something to make that much noise 'under normal condition' If any one has identified this noise please let us know!

[jajeh5]

I have never noticed this on my 03 with 30,000. I will keep my ears open.

[JeffD]

My A/C compressor kind of groans. I don't remember if it has always done it, but it is a lot quiter than my maxima compressor. My alternator also whines pretty loudly - especially under load with the A/C and headlights on.