A/C noise

Looking for an answer to an A/C noise issue. Read a lot of blogs, etc.....still can't get to the right answer...if there is one.

2008 Pre-Runner with the V-6 engine. A/C started making a noise that sounded very similar to a "low power steering fluid noise". I can only describe it as a whining noise.

It comes and goes whenever the compressor engages. Have had a mechanic replace the entire compressor, condenser, expansion valve, an idler pulley and the alternator that started to vibrate after we did all of this work. The noise still comes and goes whenever the compressor engages. It goes away when the compressor disengages and I can stop it by turning off the A/C on the dashboard.

Any further ideas? The noise sounds just like that whining noise you would hear from a power steering issue.

 

Hmmm... I just replaced my AC compressor for a similar issue. The whine went away.

I hate to point out the obvious, but have you considered the power steering pump. I believe the power steering had been somewhat of an issue on our trucks. Take a look at the fluid level.

 

Thanks for the reply. I did check the power steering fluid level, first thing. Was hoping that a new compressor was the fix. The whine only comes on when the compressor kicks in, even if sitting at an idle. Frustrating to have replaced so many parts and still have the problem.

 

Does the noise increase in pitch with RPM's?

 

It does in a weird way.....almost as if it was related to the transmission. If turning off the A/C didn't solve the problem....then I could almost suspect it to be a transmission sound. It does sound just like a power steering noise.....but it goes on and off as the compressor cycles on and off. Would really like to pinpoint this noise.....since replacing parts is getting costly and frustrating. But, it definitely is only present when the A/C compressor is engaged. Thanks for your interest.

 

Have you ruled out a worn serpentine belt causing the noise?

 

On the right track, but I would suspect a failing tensioner or idler pulley. When the compressor comes on, additional load is placed on all the accessory pulleys...including the tensioners.

 

I would agree but OP stated that the idler pulley has been recently replaced. OP, when the noise starts, try spraying water at different rotating pulleys that the serpentine belt supports to see if the noise goes away. That's one way you can try to eliminate squeaky pulleys such as alternator, water pump, a/c etc.... If the belt is old, I would replace that first before doing any tests. A worn stretched out belt may squeak with additional a/c load.

 

OK...thanks for the ideas. Will be replacing the other idler pulley and serpentine belt this weekend. Have tried reducing the amount of refrigerant in the system. ( a Toyota mechanic suggested this and said that a fully charged system could be the culprit) Reducing the charge has lessened the noise.....but it is still present when the compressor is engaged. The only other part would be the tensioner pulley. I will post any changes. Still a strange animal to diagnose.

 

How well does the a/c work? What kind of equipment is being used to charge the system? Are you certain the right amount is in there? What do the hi/low pressures look like?

If you aren't getting enough heat transfer at the condensor, the hi side pressure can go up and make the compressor have to work much harder. Try spraying the condensor down with water and see if the noise goes away

 

b_r_o

The a/c works fine. Blowing cold air....about 45 degrees. When the new system was installed....compressor, condenser, expansion valve, idler pulley (the other idler pulley will be replaced today as well as a new serpentine belt).....the system was charged using a new set of pressure gauges. The vehicle sticker calls for 1.26-1.39 pounds of refrigerant. We used two cans...which is 1.5 pounds . We have bled off some of the refrigerant and it seems to have gotten somewhat quieter....but the noise is still there. The initial readings were about 45 for the low side and 220 - 230 for the high side. Yesterday we bled the lines a bit and read the gauges while revving the engine at about 1500 rpms....the readings were about 34 and 220. (I could be off on those readings...) Still blowing cold air around 45 degrees...but the noise is still present ...but somewhat quieter.

I will pass your suggestions on to the mechanic today...about the heat transfer, etc... as well as the previous replies. Thanks for your interest in helping. JIM

 

Did you add any oil when u charged it?

 

Yes, as it was explained to me, the new compressor had some oil in it, but needed some additional oil added before the refrigerant. We did that. Also did some kind of controlled short term running of the unit ....before running it for an extended period. The oil was added as a first step though.

 

Hmm... that hi side pressure is ok, no need to spray the condensor down.

How much did the new compressor cost? Is it a reputable brand?

 

From the receipt and the part number....from Pep Boys.... I am told that it is a reliable source. The mechanic is mentioning removing the replacement and trying another one. He says it is not all that rare for replacement compressors to be faulty. Seems like a lot of work with not guarantees of a better result. The compressor with the clutch was $358 plus tax. (the condenser / drier was $96 and the expansion valve was $20) Any experience with this parts supplier.....? I know that it is not OEM.....but I am told that takes the job to a whole new level of costs.

Factory Air by 4 Seasons New Delphi SP15 Compressor w/ Clutch
Part #:68677
| SKU :996383
★★★★★
Write the first review

 

Yea trying another compressor is probably a good idea. It's kinda frustrating to get a bad one right out of the box but it happens

 

I had a similar experience when running the AC a while back. Ended up being bad alternator bearing.

 

^^^ get a stethoscope and listen around at all the pulleys and accessories while the clutch turns on and off

 

Have done the "listening thing" with a ratchet extension. The alternator was loud, so we replaced it. One of the idler pulley was noisy also, so that was replaced. Today the other idler pulley will be replaced. Should know more later today.

 

I'd have to agree. 50 psi low side and 40f vent temp? Unpossible.