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Mastertech1, ASE Master Technician
Category: Car
Satisfied Customers: 2261
Experience:  30 years of all phases automotive diagnostics and repair
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Loud..turbine..the ac/heat switch button, but kicks on since this car

Resolved Question:

heater make a loud jet fan noise when on, it is quiter whn the AC is operting I believe.

whooooooooooooooooooo is the noise , its like a turbine is kicked on a race boat .
it goe s off when pressing 0 on the ac/heat switch button,
but kicks on since this car knows no matter what, to turn ac or heater on and off even when placed on "O" position i.e., the off button, I presume .
Submitted: 5 years ago.
Category: Car
Expert:  Mastertech1 replied 5 years ago.
Hello: what you are experencing here is: something is traped in the blower wheel (fan) Possible piece of paper or ? might have fallen through the defroster vents and worked its way into the blower, Or you might have a same issues we have in my region, (mice tend to get into ducting and build nest in that area) The blower motor will have to be reemoved to clean out. Thanks
Customer: replied 5 years ago.

my neighbor had a similar issue on his Benz, he disconnected my large cooling fan plug (ie the auxiliary fan assembly ) behind the radiator, i.e., the big fan.


and the noise stopped ,


yet the AC & Heater fan I assume it still works since it was pushing air though the inside vents.


you sure its not the auxiliary fan assemblies bearings are are shot?

that part at "parts geek .com" is $600.00



Expert:  Mastertech1 replied 5 years ago.
Ok ,my mistake,Sorry,I thought you were taking about the hvac blower fan (inside the car),Then yes if its the radiator cooling fan,then the motor is bad, Yes replace the fan assembly, Thanks
Customer: replied 5 years ago.

why then when the heater is off the sound is very quite, yet when I put the heater fan to high it is a very loud noise. Its cold out , so I have no real information when the ac fan is turned on.


I'll go out now , & hit the fan on to see if it is the fan motor.


does the cooling fan speed up when one turns on the heater to high fan??


are you sure it is the cooling fan motor? i.e., the "auxiliary fan assembly"


the noise comes from under the hood, at the cooling fan /auxiliary fan assembly . same item different name right?


Expert:  Mastertech1 replied 5 years ago.

One is for the main engine cooling (cooling fan) the other is for when a/c compressor is ,A/C on or defroster is on (auxiliary fan assembly)

Customer: replied 5 years ago.

i'm ready to accept but the same original question is there, i cant be certain what you have todl me.


is the big cooling fan multi speed or are you saying there is a 2nd fan for thre ac heater defroster???


there is no fan noise when the big cooling fan is unpluged, but when pluged in it makes a fan noise then when I turn the ac/heater/defroster on , and turn the fan sped all the way up---

the large cooling fan i.e., the auxiliary fan assembly fan makes a loud fast whooooo noise.



Expert:  Mastertech1 replied 5 years ago.
YES, The larger fan is the multi-speed (verys with the amount of voltage applied to it,via relays), Replace the large fan motor assembly. Thanking you in advance.
Mastertech1 and 6 other Car Specialists are ready to help you
Customer: replied 5 years ago.
you r tech answere and especialy the scheematic hperlink showing where the air ride compressor and lines etc. are located disapeared from my JA questions area, can you send pics of the air ride sytem for my S500 Merceds 2001 built in Nov 2001
Expert:  Mastertech1 replied 5 years ago.
Do to copy right laws,I am unable to copy and send. Thanks

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