Car sounds like Fridge


I have a Toyota Carolla 2011. While driving it makes a rotating humming sound similar to a fridge. Sometimes it is loud. Sometimes I do not hear it at all. Looks like it is coming from the center/center-right of the car hood. I recently changed tires and tire alignment. It did not fix the problem.

Please suggest any remedies.

Do you have a fridge in the car?


No :slight_smile:

It is usual car sound + fridge sound coming from the hood area.

Possible exhaust leak from some place near upstream?

Heat shield?

Does it happen only when you are moving, or when the car is still too?

Leaves in the heater fan?

I am not sure. How can I find out if it is exhaust leak or from Heat shield? When the car is making sound, if I stop the car and keep it running, can I find something leaking to the floor?
I will check if it is the heat shield rattling…

Jtsanders: it does not happen when I just start the car. It usually starts after few minutes. It tends to get louder with the speed. But after driving for a while, even I am not moving, I think I can hear it as a low humming sound.
I will pay more attention when it actually starts…

wentest: I do not think so. I think I feel the vibration along with the sound. But it may be just my thinking.
I will double check the heater fan again, just to be sure.

A problematic wheel bearing makes what most people call a “growling” sound that gets louder the faster you go, but at lower speeds can sound sort of like whirring. Does the sound change when turning at a medium speed? If so, does it get worse turning left? Or turning right?

Water pumps can make a whirring noise too, as a prelude to failure. Check your coolant, make sure it is topped off, and that there are no leaks on the driveway under the car. If it is the water pump, it will get louder when you rev up the engine in the driveway; you don’t need to be moving, just the engine running.

With any engine sound, make sure the engine oil and transmission fluid are at the correct level.

A mechanic can use a tool called a mechanics stethoscope to narrow down where a sound is coming from. That’s always an option.

Is it your electric radiator fan(s) cycling on and off?

George_San_Jose1: Sound does not get louder with speed after a particular sound level. Few times, I could be going 60 and no sound at all. Few times, it starts off at 30. Once the growling sound reaches a certain level, it does not get louder with speed. But it becomes almost inaudible when I stop at a traffic light. I will pay more attention when I turn.

I will check the coolant and the leaks and pay more attention generally.

Engine oil and fluids are ok.

oldtimer_11: it does not appear to be radiator fan. But I will check, just to be sure.

If you hear it as you pull to a stop, open the hood and listen for the sound. See if you can locate it under the hood. BTW, don’t lean over the engine if you have loose clothing on that might get caught in the drive belt.

Those symptoms aren’t consistent w/what we normally hear here for a wheel bearing problem. I suspect it is something else. Differentials can make a noise like that if the transmission fluid is low.

You could do a couple of experiments besides the ones already suggested. For example when you hear the noise at say 50 mph, press on the brakes a little. How does that affect the sound. Same idea, but this time shift into neutral and coast. Any effect?

Thanks a lot for all the suggestions. It helped me in approaching the problem in a systematic way.

  1. I checked the fan. It looks good. In parking and revving up the engine no sound.
  2. There are no oil or any other leakage on the ground.
  3. Driving more than 10 miles on highway with AC off - no sound
  4. Driving 10 miles with AC on - no sound (probably less than 15% of the sound, which is not a big problem).
  5. Turned on heater and within few minutes I could hear the sound.
    If I stop at the traffic light, sound stops. And even if I rev up the engine at the traffic stop - no sound.
  6. Apply break during the problem, sound reduces a bit, because of the reduced speed.
  7. Turn on the heater when parked and rev up the engine for a while - no sound.

It looks like the sound is only when heater is on and car is moving.
Is this related to heater pump, maybe?

Car sound loaded to youtube. If you listen in high sound, you can hear the “growling” - Car sound


Heater pump ? Change the fan speeds and see if that makes a difference.

VOLVO_V70: I mean to say it must be linked to heater device. I am not sure how AC/heater works.

You mean the speed of heater in the dial? Usually 1 to 5? yes, when I change the speed, the sound varies. Not immediately, but within a few seconds, the sound varies.

What is causing this sound? Do I need to clean up the heater? How do I do it?


If you can turn the noise on and off by turning the blower motor on and off it must be a noisy blower motor but if that is the case it should be noisy if the car is stopped or moving.

Nevada_545: noise is not 1 is to 1 with the AC/heater unit. Sounds seems to come from just behind the passenger glove box. I will get the blower motor checked and see if it makes any difference.