Groaning sound when come to complete stop: only when A/C is running?

the compressor is more of a whine than a groan. sure it's not surface rust on your brake discs? record the sound and post it up!

 

I had something similar to this the other day. When the a/c was running hard and the HV battery was down to two bars whilst I drove in heavy start stop traffic, I would get a vibration through the brake pedal when I came to a complete stop. It only lasted about 2 seconds but occured about 20-30 times over a 5 minute period, and would happen at the point the vehicle actually stopped - almost like a pump or a compressor operating. It wasn't noisy or a harsh vibration but you could definitely feel it through the brake pedal.

Never done it before, not done it since but I did think of this thread when it happened and wonder if others have had similar happenings? Just seemed strange as it's not happened before and wonder if the low battery and heavy a/c use might be a cause?

 

Sure sounds like the hydraulic brake pressure pump. Especially as it occurs after you actually -use- the hydraulic pressure.

You probably didn't notice it when you were not using A/C as you probably had the windows open a bit. The outside noise can easily mask the sound. Windows closed Prius is very quiet. You can hear a lot of the mechanical sounds.

 

Our 2010 Prius makes a fairly loud groaning/whining noise when the A/C is on; when I turn the A/C off, it stops. I'm going to mention this to Toyota when it goes in for the 10,000 mile check as it seems to be getting louder.

Just saw there's another thread on this and supposedly it is "normal." I think the reason we noticed it so much today is that it's 93 degrees here and according to the thread, the electric compressor makes more noise the hotter it gets and the harder it works. VERY annoying!

 

yesmy car makes the same noise when i stop as it does when i open the door the first time. Sounds like the brakes doing thier job.

 

I think the real reason is your not running the ICE while stopped!! Thats why you can hear the ac running. It's really a good thing the ac noise is not covered up by a gas motor burn gas at a stop light!!

 

Probably some truth to that but our G2 never made as much A/C compressor noise as the new G3 does. Perhaps a different type (scroll) compressor? Inverter?

 

Honesty my car ac makes very little noise, it there is another car in the area running it will drown out the ac noise from my car. I would say my car is 2x louder when it idles the ice at a stop than running the ac.

 

Do you notice that it is louder when the temperature is higher and it has to work harder to cool the cabin? The whining/buzzing is louder in our car as the ambient temperature goes up and when the cabin is hot after the car stands in the sun. Don't notice it as much in spring & fall and not at all when A/C is off.

 

We just returned from a weekend trip, and I've noticed the same grinding noise. Motor off , a/c on, loud groaning/grinding which gets slower if you lower the fan speed, and stops completely if A/C is turned off (fan still on). It sounds to me like the A/C compressor has a bad bearing. I also noticed, when I turn off the A/C, and take a look at the site glass by the "HI" side A/C line, it's bone try, and a couple bubbles of liquid try to make it up the tube into and by the glass, but I'm thinking there should be some liquid inside the site glass. My recollection was the site glass was to look into to see if air was in the line, ie. look for bubbles, but I'm looking at air, looking for liquid bubbles? Can somebody turn their A/C on for 5 minutes, turn off the car, wait two minutes, and tell me what you see through that site glass? Taking it into service tomorrow, as there is no longer the capability to drive "quietly" in the Prius with the A/C growning like it does. Annoying. I've had the car for almost a year and never heard this grinding noise, it's a new one to my Prius. Just turned over 16K, and never had an issue other than rattles and the brake brain reburn. I'll follow up a post after the service call.

 

Well, the dealer put a new compressor in Friday (said there was a lose piece in the compressor and it would be sent back to Toyota), and said it was charged with new fluid, but has a green dye in it (unlike the clear from the factory). Ran the car this week, still groans and vibrates (can feel the compressor vibration via steering and brake pedal), and still now liquid visible in the site glass. Basically, it's doing the same, but I have a new compressor and a fresh charge, so I guess it's the nature of the beast. No more stealth mode with the a/c running. Sounds about like the noise you get from a radiator fan running.
Would still like to get a confirmation from one of you out there on that empty site glass while the A/C is running, and just after the a/c is turned off.

 

Did you record the noise?

 

No need to record the noise. I took it over to the dealer and traded her for a red IV solar package. Wow, leather is nice! Oh, and the a/c makes noise, and the site glass has no fluid. the dealer said they fill the a/c based on refrigerant charge weight, not by the site glass, so I guess if you see liquid in your site glass, maybe it's been overcharged. Who knows? Had the side moldings put on, which give the car nice lines on the side, but probably add wind drag. I hate door dings, so it's worth it to me. Anybody look at their a/c site glass after they shut off the a/c, yet?