Grinding sound when ac on

Brique

Brique

New member
So we finally got some weather hot enough to require turning the ac on today. As I was getting on the highway I heard a short half-second grinding noise coming from the passenger side of the engine bay. Sounded a lot like the noise you get when you try to start the truck when the engine is already running. A couple minutes later it did it again. Very short. Couple minutes later, same thing. I turned off the a/c, having deduced that I believe the compressor is on that side of the bay and this is the first time I've used it this year. Didn't hear the sound again. Five or so minutes later, I decided to turn the ac on to see if it would cause the noise. This time the grinding started immediately and kept grinding. I immediately shut off the a.c. and left it off.

Thoughts?
 
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Brique said:
So we finally got some weather hot enough to require turning the ac on today. As I was getting on the highway I heard a short half-second grinding noise coming from the passenger side of the engine bay. Sounded a lot like the noise you get when you try to start the truck when the engine is already running. A couple minutes later it did it again. Very short. Couple minutes later, same thing. I turned off the a/c, having deduced that I believe the compressor is on that side of the bay and this is the first time I've used it this year. Didn't hear the sound again. Five or so minutes later, I decided to turn the ac on to see if it would cause the noise. This time the grinding started immediately and kept grinding. I immediately shut off the a.c. and left it off.

Thoughts?
Click to expand...

Blower fan would be my first guess:
http://www.toyota-4runner.org/3rd-gen-t4rs/113266-cleaning-blower-fan-write-up.html
Unless it doesn't do it with just the fan on.
 
Nope, not the blower. With blower running, no problems, but the moment I hit the a/c button it starts grinding.
 
So the a/c cools as it should otherwise? Checked the sight glass for small bubbles after it has had enough time to equalize high/low pressures?
 
jgue467 said:
So the a/c cools as it should otherwise? Checked the sight glass for small bubbles after it has had enough time to equalize high/low pressures?
Click to expand...
Don't know if it cools, I shut it off as soon as the grinding started for fear of tearing something up.

Um, tell me more about this sight glass you speak of. I'm not familiar with it.
 
Ac compressor clutches die all the time. A good telltale sign is a red rusty dust in the area of the compressor. Another method of diagnosis is to use a mechanics stethoscope, very very handy for finding seizing or bad bearings. If it cycles with the ac compressor I would say it's the clutch.

Sight glass is behind the grille on top of the accumulator(?), left hand side I think.
 
Didn't see any dust when I looked. Couldn't find the sight glass, but rereading your post, it appears I was looking in the wrong place.
 
Yeah, I was worried about that.

The plot thickens a bit. While I was at [MENTION=87436]ugamurph[/MENTION]'s house today we fired it up and it was silent. Not sure what's going on.

Honestly, I don't mind replacing the compressor if I have to, my biggest concern is if the damn thing disintegrates and I end up having to redo my entire ac system.
 
You need an ac machine to draw down the freon when you change the compressor, and then to re charge it again. Best something left to a shop. There is special oil that has to be injected into there at the same time.

Clutches are non serviceable. I would just buy a reman compressor or find a good used one...
 
Bother. I was afraid of that. Looks like I'll be dropping by the dealership to have them look at it today.
 
Brique said:
... we fired it up and it was silent. ...disintegrates and I end up having to redo my entire ac system.
Click to expand...

Silent as in zero operation/no cooling? Compressors aren't that expensive on ebay/amazon. Just find a competent mechanic to install it. Make sure to install a new drier or add one if oem and a new orifice. Process is simple, its all about cleaning and evacuating the system of all contaminants. Luck!
 
Yeah, turned it on again yesterday and it ran fine, no noise. That said, I'm still having it looked at. Don't want to put it off and cause a bigger problem later.
 
Paperjam said:
You need an ac machine to draw down the freon when you change the compressor, and then to re charge it again. Best something left to a shop. There is special oil that has to be injected into there at the same time.

Clutches are non serviceable. I would just buy a reman compressor or find a good used one...
Click to expand...

I always thought that the clutch was a separate item that could be removed from the compressor and replaced?

I found this thread discussing that:

http://www.toyota-4runner.org/3rd-gen-t4rs/129607-ac-compressor-clutch-replacement-do-not-do.html
 
So, took it to the dealership yesterday to have it looked at. The tech (who I know personally) told me he couldn't hear anything wrong with the compressor, but that the idler pulley for the ac belt seemed a little iffy. He said if it was his truck that he'd replace the pulley himself and let it ride on the compressor.

The service advisor had a different story. She said the compressor needed replaced and quoted me $1300 for the job, of which $615 was for a reman compressor. I told her I couldn't do business with them. Profit isn't evil, but charging $615 for a reman unit when I can buy a brand new oem unit online for $360 or a denso "aftermarket" unit for $250 on Amazon is just beyond ridiculous.

So, in summary, I'll be ordering a $20 ac idler pulley and changing it out in my garage.

Thank you to everyone who posted to help me out, I'll keep you updated if it starts acting up again and if it does turn out to be the compressor.
 
Brique said:
So, in summary, I'll be ordering a $20 ac idler pulley and changing it out in my garage.

Thank you to everyone who posted to help me out, I'll keep you updated if it starts acting up again and if it does turn out to be the compressor.
Click to expand...

Good call. Unless it's constantly screaming at you, I'd try the cheaper/easier part first. If it doesn't work, you're out $20, and the idler may be worn even if the compressor is bad.
 
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