bobolee

Ok, I've had problems with my heating, all cold air and no heat, so I decided to switch the vaccuum hoses as many have done here. That seemed to work. I now get warm and cold air. However, whenever I have the A/C button pressed, there's a squealing noise that's coming from the engine compartment. When the A/C is off, the noise dissappears. Any suggestions???

RX469

iTrader: (1)

hmmm, sounds like your belt is dry or may be loose?? Did you check the tension and condition of the drive belt or the one on the a/c.

BLK13X

Welcome to CL.

One of your bearings may be seizing up (like what happened to mine... then I snapped the drive belt).

simonsays

this is happening to mine too!
like it comes and goes. can it be something to do with the fan?

salimshah

Observe and conclude. Does the noise come when the a/c compressor clutch engages [idleing level changes the load on the engine increases] ... very similar to ac at home kicks in from signal from thermostat.

If is so you have the belt slippage. As pointed out the belt slippage could be due to one or more items running off the belt is not moving smoothly or the slack on the belt is too-much. As pointed out the tesioner is supposed to take away the slack.

Once the belt has slipped enough times, a layer of gloss comes on it and even if all the componets riding on the belt are fine, the belt slips. Solution is to replace belt. Belt dressing are available but they tend to be a temporary fix. It might be worth spending money on the dressing to help you isolate the problem.

Salim

RX469

iTrader: (1)

RX469
Salim
Very well said, that's what I meant to say.

e-man

Hey SalimShah. I think I have the same noise. I have a 99 GS400, and mine sounds like crickets chirping through the vents. It's very faint, but still annoying. If I turn the fan up, the noise is muffled by the fan noise. I have been able to pinpoint that it's definitely the a/c and not the blower motor because the noise goes away when I turn the a/c button off (while leaving the fan on). Could this be the belt that's driving the a/c that's making the noise even though the noise is coming through the vents?

blksc300mt

look at the crank pulley....the part that drives the belt can come loose from the rest of the pulley, and when it first does this you can get by for a little while, but when you put the extra load on the engine with the a/c compressor, it'll sound pretty bad

salimshah

Some have pointed out the blower motor at low speeds makes a chirping sound [TSB on various Toyota models as well]. The venting options [mode] can divert the air flow and noise conduit. So I would be little cautious in discounting the blower motor.

Try the belt dressing to eliminate the belt. Some have suggeted misting the belt with water [do not douse water on hot engine]. Sound from the belt has to penetrate the cabin throught the fire wall or windows. So theratically you shold be able to hear it with the hood open while parked.

Salim

e-man

Thanks Salim. The noise is definitely emanating from the a/c and it's coming through the vents. Like I said, when I turn off the a/c button, the noise goes away. It's such a faint noise that I'm really not concerned with it. Is it possible that a squeeky drive belt can be heard through the vents? Next time I hear the noise, I'll pull over and pop the hood and see if I can hear it.