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98 Nissan Frontier A/C squealing - clutch or idler pulley?

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New User

Jun 18, 2022, 7:43 PM

Post #1 of 3 (383 views)
  post locked   98 Nissan Frontier A/C squealing - clutch or idler pulley?  

Hi all -

I have a 1998 Nissan Frontier, 4WD, 2.4L 4-cyl, around 175k miles.

My A/C has developed a bad squealing sound. It will typically squeal for 15-30 seconds when I turn it on, or pretty constant when I accelerate hard - or as hard as you can in a 4-cyl Nissan truck.

The air conditioning belt did show some wear, so I replaced it - and it did seem to quiet down for an afternoon. The next day it was just as bad - if not worse.

I'm considering trying to replace the compressor clutch. However, I'm wondering if it could possibly just be the idler pulley.

Would anyone have an idea on how to tell definitively whether it's coming from the compressor clutch or the idler?

I'm starting to have to throw more money than I'd like to at a truck this age - so I'd really like to be able to diagnose what's going on.



Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 19, 2022, 2:43 AM

Post #2 of 3 (364 views)
  post locked   Re: 98 Nissan Frontier A/C squealing - clutch or idler pulley?  

Take the belt back off or out of the way. Spin idler and w engine off spin the clutch it should free-wheel. It or those items should also be about silent no play and no noise really. Check all pulleys - PS and water pumps will not coast for you others should free as a bird.

IDK, idlers/tensioners have marks for the range they will operate in so look for those - mark them see that it's in the middle give belt room for its range.

Squealing could also be an overcharge? Anyone mess with refrigerant charge amount - specifically ADDING ANY? If so it has to be discharged and filled to spec - exactly.

So far this smacks of an overcharge A/C is dragging almost or actually choking on refrigerant IDK that nor do you without taking it all out and filling again to exact ounces it calls for. If clever with scales (postal grade) use tare weights vs what's left no overfill a system!


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 19, 2022, 4:14 AM

Post #3 of 3 (356 views)
  post locked   Re: 98 Nissan Frontier A/C squealing - clutch or idler pulley?  

This is definitely not something to ignore but don't jump to conclusions.

The one thing that will not help is replacing the clutch. That is not causing the noise. The noise is coming from the belt slipping, the question is why. It would be nice if it's something as simple as an idler pully or tensioner but not real likely. The most common cause is the compressor starting to seize up for whatever reason. It could be overcharged as Tom suggested but continuing to run it that way will lead to total destruction in short order.

Get it checked out ASAP.


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