AC compressor whistling . . .

Hi all, I have a '17 Tacoma SR5 that I bought new, has 30k miles on it now.

For some time now I've heard a faint whistling/howling sound coming from somewhere. At first I thought it was coming from the radio; I shut it off but the sound didn't go away.

Then I noticed it happened roughly between 2,500-3,200 RPM, comes on kinda gradually and cuts off quickly. Still couldn't really tell where it was coming from. Then I tried shutting the AC off, and that was it, no more noise.

Any idea what the problem might be? Any easy fixes possible? I'm too old to be dicking around much on vehicles so I'll take it to the local garage if need be (good guys).

 

https://static.nhtsa.gov/odi/tsbs/2022/MC-10207964-9999.pdf

Not an easy fix. Big labour bucks.

 

Might be as "simple" as replacing the magnetic clutch on the compressor. Only a good tech knows for sure. Been there once on my '06 TRD OR.

 

Hey thanks for the quick reply. I looked through that, the symptoms are close.

So approximately how much to have it done at a garage/dealer?

 

Thanks. I guess I'll have to take it somewhere. As I noted above, the symptoms are close but not quite what the article described.

 

Got a rough idea of the cost?

 

1600-1800 seems to be ballpark.

 

Is this where they tear the dash apart to fix this issue? Is the whistle like the one posted in this thread? If so, mine has done this from day one. Don't know if I want my dash ripped apart. Even under warranty. Maybe I can put up with this as It's sporadic.

 

my original evaporator core had a leak and needed to be replaced. the dealer wanted $1500 but was booked for a month, so i took it to an a/c shop and it was $1800.
before i didnt have the whistling sound, now i do..

 

I checked that post, and that's exactly what mine sounds like. I also read the first page of comments.

As noted in my OP it only happens roughly between 2,500 and 3,200 RPM in any gear, so whatever it is it's RPM specific.

This whine has been going on maybe 2 months, so it's something new that didn't happen the previous 29,000 miles.

FWIW, the AC still works fine.

 

My truck had this whistle since day 1. I thought it was weird but never thought it should be looked at. I may take it in after all.

 

I was told by an HVAC person that it's normal in some vehicles. The whistle happens from the quick expansion of the refrigerant going from liquid to gas in the evaporator.

 

I wonder why mine did not do it for the first 29,000 miles of its life . . . ? Plus, it only does it within a certain RPM range, regardless of outside temperature or anything else.

 

Might have something to do with refrigerant pressures when the engine is spinning the compressor that fast? I'm no HVAC expert, just my 2 cents.
Not sure as to why it would creep up now. My last truck did it (2005 Chevy Colorado) and my Taco has been doing it since new.

 

I have the same issue in a 2020. Does this cause any long term issues? I can deal with it so long as it wont cause further issues. Id rather they dont get in there and take things apart if its not necessary.

 

Mine has done it since day 1 as well under acceleration.

@Bishop84 - can you clarify if this condition causes any actual damage if unresolved or I just have to put up with the whistle? I've heard that noise on other ac compressor systems with expansion so I can't imagine this will somehow cause permanent damage.

 

Some more bits of info:

Today when I got home, I left the truck window down and opened the hood, AC was on. The compressor was cycling on and off, no unusual noises going on. Although the squeal, as previously stated, only happened between 2,500-3,200 RPM as far as I could tell while driving.

I've heard it before, but not consistently, while sitting still with the hood open, revving it up. When I get somebody else here, I'll have them rev it and I'll stick my head under the hood.

FWIW, it was around 88 today on the way home from lunch so the AC was working pretty hard, but the squeal was not as noticeable as usual.

 

Mines done it from day one. Never any issues though. AC works great.

 

Unless there is a long term reliability issue, not sure I would have my dash taken apart even for free under warranty. Probably end up trading one noise for three others from poor reassembly.

 

it's not really a mechanical issue, just annoying. i'd be hesitant to have a dealership rip my dash apart for something that's normal.