loose a/c belt or dying a/c compressor?

[berge]

our 99 nissan quest is giving a loud screech from the engine bay for about 3-4 seconds IF I turn on the a/c while acclerating hard. I can consistently duplicate it. Also, sometimes, while the a/c is already on and there's hard acceleration, the same sound appears for roughly the same amount of time. the belts have roughly 10K on them and the a/c belt looks in far worse shape then all the others. operationally, a/c system works fine.

loose belt, or bad compressor clutch (new compressor or repairable?)

or something else
(all non engine/transmission components on this vehicle are FORD, BTW)
thanks.

 

[Drew99GT]

Grasp the A/C belt and check to see if the tension feels a little loose. That likely is the problem. I checked a parts store website and your vehicle has a seperate A/C belt and likely a manually adjustable tension setup.

 

[PandaBear]

One mechanic friend to me to spray a small amount of water on the squeaking belt, if it stop squeaking, it is the belt.

Some other car site I visited suggested using soap to lub it, I don't like residue too much, so I am do not recommend personally.

Don't spray too much though.

 

[kenw]

the water trick is a good way to see if it is just slipping, if so a longer term temporary fix is to spray a bit of belt dressing on the belt to soften up the surface.

 

[Matt_S]

If this were me, I'd do the following:

1) Check the tension. Tighten it up if necessary.
2) If that doesn't fix it, just replace the belt. Since the problem apparently doesn't appear at idle, the water suggestion won't be practical. Belt dressing, at best, is a temporary fix and IMHO, you'd be wasting your money there.
3) If a new belt still squeals or if the squeal resumes after a relatively short time, you'll know you have a compressor problem.

 

[berge]

thanks.
I will check tension first.

does anybody have first hand experience with somehthing called 'black death' on ford a/c compressors?

thanks.

 

[Tosh]

No, but I'm dying to find out....

 

[Chris142]

quote:

---

Originally posted by berge:


does anybody have first hand experience with somehthing called 'black death' on ford a/c compressors?

thanks.

---

Yep I do. I see it often.

Pag oil attracts moisture. The rumor is that they left many open barrels of the stuff outside and they got rained on.

Add R134a, pag oil and water you get Hydrocloric acid. This acid eats everything aluminum in the system which plugs the orifice tube. Then the compressor grinds up due to lack of oil.


The only way to fix the damage is to replace every part including the condensor, evap, lines drier and compressor.

Don't even try to be cheap and flush any parts as the new compressor will be contaminated with trash and die immediatly.

 

[darryld13]

Is it possible that the pulley is somehow out of alignment or a compressor bearing out of spec to the point that the belt flops erratically? Can you replicate the problem while parked and the hood open to observe? The considerable wear on the belt and squealing sounds like a possible belt/pulley problem.

 

[berge]

I duplicated the problem for the mechanic in his shop. vehicle in park, rev engine to 3000-4000rpm, hold there, turn on a/c. voila.

it took him .1223 seconds to say 'yup, a/c compressor clutch', but all the diagnostics I read on the web (searched here, gates.com, etc.) points to a loose belt, pulley issue.

I have the factory service manual for this car. when I have time, I'm going to just change the belt and check tension, alignment and go from there.

 

[punisher]

The only "black death" I am acquanted with is on the FS-10/FX-15 Ford compressors. I don't know about the hydrochloric acid, but the black death refers to the particulate matter that gets released when the compressor's teflon piston seals let go. The seals fail, the piston scrapes on the bore and pieces of black teflon and aluminum particles get in everything from the high side lines, condenser to the orifice tube. It do get nasty. Sometimes you get a nasty black tar type material in the lines as well that can't be removed with any shop solvent I have run into. If it progresses that far, you can write off another $400 in parts for an AC job.

If that Ford compressor is knocking, waiting too long to replace it can cost a small fortune due to the components it trashes.

If you are going to do the clutch yourself remember the snap ring pliers, and get your hands on some clutch shims if your kit doesn't include them. Shimming the clutch on the low side of the clearance specs will really cut down on the clicking noise upon engagement.

 

[Matt_S]

I'm glad it was that simple. Hopefully this solves the problem permanently.

 

[berge]

thanks

 

[berge]

update.
belt was VERY loose.
didn't bother tightening, just changed with new oem belt.
no more squeal.

fairly disappointed in the mechanic though.

thanks all.