talwang

iTrader: (4)

I changed the AC mode a few times and was driving for about 40 min this morning, but I still haven't experienced any of the bb's you guys had described.

kleef

I've tried it all now... switching off the VSC, trying every mode of a/c, and stilll the dreaded BB's. Time to go back to dealer!!

kleef

As an update to this thread, currently my car is at the dealer to check out this problem again. Now they tell me there is air in the cooling system that is causing it. I am hoping that this fixes the problem. Does anyone know: Does the cooling system circulate near the front of the car near the dash? That's where I hear the "rolling bb's" sound when i accelerate after a stop.

Habious

Yup. The liquid from the cooling system flows through your heater core (deep inside the dash by the firewall). That's how you get hot air from the vents.

paul_k

I'm getting the buzzing noise from deep behind the dash but seems to be only on roads that are not smooth and have a gravel type finish. It can only be heard slightly with the audio turned down a bit.

I think there is something resonating at the same frequency as the road surface but could be wrong.

I will take this up with the dealer.

BigManne

iTrader: (3)

air in the coolant system?

kleef

THE PROBLEM IS SOLVED! It turned out to be air in the cooling system from last year, when Lexus Kearny Mesa performed the 30K service. It took three trips to the dealer to get that figured out. Now it's so obvious. Hopefully this thread will help anyone else who has the same problem.

BigManne

iTrader: (3)

oooo do i win a prize?

tm510

Sorry, but I'm still confused about this. "Air in Coolant system"?? You mean, you needed to open the radiator, and get more fluid in, ie. more air out?

If so, what technique would be required to achieve this?

thanks,
Jerry

kleef

Lexus told me that there was air in the cooling system (I don't think this is related to the radiator, I think it's part of the heat exchange system for the ventilation... or is that the same?!!!). They said they bled the air out. I know very little about this stuff.

BigManne I think the best prize is that you won't need to take your car in 3X to figure it out if it ever happens to yours!

tm510

Fluid running thru your heater core, I believe, is the same fluid running to cool your engine. There is only one reservoir.

So if you understand this, and can explain it better, that'd be great.

tfeni52355

Cars have both a heater coil (like a radiator) and an A/C evaporator coil (like a radiator only in reverse) inside the dash.

The heater coil takes hot fluid (water/antifreeze) from the radiator circuit in the engine compartment and runs it through the coil when the heat is on. The fan in your cars dash runs air over the coil to heat the interior.

The A/C evaporator coil uses refrigerant (freon R-134) and actually pulls heat from the air as the fan blows air over it. Doing the reverse of the heater.

My guess is the A/C system caused the BB's sound. The radiator circuits in cars are self bleeding and air naturally is eliminated from the top of the radiator through the black hose that goes to the coolant tank. The A/C circuit will be noisy if there is not enough freon in it. I.e. air in the lines instead of freon. Once the technician adds freon to the A/C circuit it will eliminate noise. The noise is actually due to expansion of the freon in the coil happening in an inconsistent manner due to air in the circuit and not enough freon.

Hope this helps!

tm510

Yes, and thanks.

Great explanation, and I know where I'll look first if I think "bb's in my dash".

Thanks,
Jerry

BigManne

iTrader: (3)

it already happen on my GS. it was an easy fix.