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Belt Squeal When Ac Is Engaged???


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Any Diagnosis




Brand new Korman Motor.  Just broken in last week.  


AC works and blows hard and cold, but when accelerating or idling and warming up, This is what I hear.


My guess is a loose belt?  Water pump is new.  The entire engine and AC is new.  (AC approximately 1.5 years old from http://www.iceautoair.com)  It has performed well.


Any thoughts?






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That sound in the video clip and your description of when the squeal occurs (engaging a/c, accelerating and during warm up) confirms that it's a loose belt.


If the sound, caused by the belt slipping, goes away after the engine is warmed up it means that you only need a very slight adjustment to the tighter side.  Don't make it too tight or you might accelerate the wear on the bearings.


A quick and dirty way to confirm that the belt is slipping slightly is to give a couple of squirts of "belt dressing" from a spray can made specifically for that purpose, to the inside of the belt while it's squealing: http://www.amazon.com/s/ref=nb_sb_ss_c_0_13?url=search-alias%3Dautomotive&field-keywords=belt%20dressing&sprefix=belt+dressing%2Caps%2C303


If the squealing disappears immediately, you have found the cause.


Note that some don't like to use belt dressing because it has a negative effect on the life of the belt, but I don't know how accurate that assessment is because others say it conditions and extends the life of the belt.  :wacko:


Regards, Maurice.

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With the engine off, take a look at the sides of the A/C compressor V-belt.  Are they kinda shiny?  If so, the belt's been slipping, and the more it slips, the more it's gonna slip.  Try tightening first (but not too much, see above).  If that doesn't help, a coupla thoughts:


1.  make sure you have the correct length and (especially) width belt.  If the top of the belt is way down in the pulley groove, the belt is too narrow.  Riding deep in the pulley will make it overheat and stretch--and squeal.  Had this happen on my 73--auto parts store sold me a belt that wasn't wide enough--lasted about 400 miles--on a 1000 mile trip!


2.  If it's the correct belt, tightening doesn't help and you don't want to buy a new one yet, there's another trick, but you must be VERY CAREFUL doing this.  With the engine idling and the belt turning, carefully hold a piece of sandpaper against each side of the belt to deglaze it.  Do this on output side of a pulley and wear gloves--a belt isn't worth losing a finger!  Or you can just deglaze the belt with the engine stopped, or remove the belt.


Bet it just needs tightening, unless the wrong belt (too long, too narrow) was installed.



Edited by mike
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