Really bad whistling noise.

[Stewart G Griffin]

i have a really bad whistling noise only when moving.   If i turn the fan on full sometimes it goes away completely.   Sometimes it will get softer.

Any suggestions?

[zieg85]

Air seal somewhere.   Does it go away if you crack a window open slightly?  My wing window on my 85 started yesterday for the first time...

[Stewart G Griffin]

It seems to get a little quieter if i crack the window.   But only a little quieter.

[Captkaos]

Where is it coming from?  Window, door, floor, AC, Vents?

[Stewart G Griffin]

Not sure---seems more to the passenger side.  It's LOUD.

[VileZambonie]

Whistling or squealing? Unplug the blower motor and see if it stops.

[Lt.Del]

alternator bearings?  water pump bearings?  blower fan bearings (already mentioned)?  Or, all the women on the sidwalk actually whistling at you as you go by? 

[Stewart G Griffin]

It basically went away, but i'm thinking it's something under the dash so i'll be checking that.   i don't think it's the blower because if anything it starts to go away if i turn ON the fan.

i know it's not the alternator or water pump.

[VileZambonie]

 i don't think it's the blower because if anything it starts to go away if i turn ON the fan.

If it goes away when you turn it on it's most likely the blower motor. - Very common for them to squeal

[Stewart G Griffin]

So it moves even when it's turned off?

[Lt.Del]

you can't turn the blower off---at least not on my trucks.   Lowest setting, the blower still runs very low---something about keeping a positive air pressure in the cab or air circulating or something I've heard like that.

[Grim 82]

It always runs to keep the plenum dry.

[Stewart G Griffin]

i.c.---will check the blower fan.

[jaredts]

It always runs to keep the plenum dry.

Do you mean the cowl?

[Grim 82]

No, I mean it prevents condensation in the box where the fan blows at the heater core, and the related ductwork. Not exactly sure what it's called, but it's a plenum of sorts.