2003 Nissan Altima, Air condition makes loud noise when the unit is turn on. It slows down where u cant almost hear it after you turn the fan off.

ANSWERS: Oil Loss, Buzzing Noise, ETC. - Nissan Forum ' Nissan Forums

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Buzzing noise at 2000-3000 RPM - Nissan Forums : Nissan Forum

www.nissanclub.com/...nissan-altima.../128490-buzzing-noise-2000-300...

Oct 28, 2003 - 6 posts - ‎3 authors
The "buzzing noise"; I can tell that I am not alone in having this problem but has someone figured out ... I fit does, that eliminates the brake rotors, tires, wheelbearings, CV's etc. ... BUT with an Altima it is probable the pre-cats. Loud humming noise when driving
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Knocks ---big ends or main bearings
rattles-----tappets worn or loose or hydraulics leaking down too fast
Tinny noise ----water pump bearing , fan hub.
Sharp release of air noise --- broken exhaust pipe
for starters
Take your pick

Its probably back-firing in the intake - which means it is firing early or the fuel mixture is very lean.
This engine uses a distributor cap and rotor, so I would start there and make sure the cylinders are firing correctly.
If the ignition checks out ok, it could be a problem with the cam timing.

most def you need an alignment and you also need to check inner outer tie rod end and check the tires belt as well

No that doesn't sound like the problem, the fan clutch locks up to cool the engine off due to the increased load of the AC system on the cooling system, so it locks up and gets much louder. If it didn't lock up the engine would overheat.

Tell me when you speed up is the heater set on hot and high speed?????
WHEN you slow down is the fan still going at the same speed or dose it go very slow when on idle.
If the Fan stays on high but runs cold when going about 80 in top but when you speed up it gets hot and then back off slightly then its sounds like Water pump isent pumping the water around the engine correctly ,but then it should make the engine run overheated.or it could be a slipping fanbelt, but then that should make the Alternator to make a noise,so {throttle to 2000 rpm from idle standind still} and see if there's a noise coming from the water pump area.
The belt should have just a little free movement more on the longest part of the belt(a very little about 1/8' movement
So check it out and let ne know how you get on .
Ron

verify the radiator fans, fuses, relays of fans. when you turn on the a/c all the radiator fan turn on too, if not you have a problem with it.

sounds like the clutch on the compressor to me and they are not sold seperatly so you are looking at about $600, sorry to be the one with bad news.

1st check the the oil level and the vehicle's oil type.(owners manuel) 5w30-10w30
10w 30 is a thicker oil and could possibly be causing this.(Moves more freely through the engine heats the oil)

it could be the valve lash, try an oil change.