Hi all, my wife's 04 V8 Limited 4WD all of the sudden started making a loud whining noise when AC is turned on. Does this for3-5 seconds and then goes away, but AC light blinks after that. Turn AC off and back on, it does the same thing. Switched relays, but no help. Looks like the clutch is trying to engage, but is slipping. She said it has been squealing a little on startup for the last few weeks, but nothing too bad and not every time.

I'm ok with replacing the compressor if that's what it needs, just wondering if there is any way for me to tell if it grenaded the rest of the system without taking it to a shop.

Does it get cold? Could just be a bad clutch. That's good, if the pump grenades, guaranteed you get particles of metal down stream that would cause problems down the road if not dealt with.

Is the squeal, metallic sounding??, your statement is a lil unclear, is the ac still cooling??. does it make the sound for 5secs and stop or the sound is continous??

am thinking along the lines of lack of oil in the compressor, and its binding/going bad. you would have to change your condenser as well if thats the case

Just pop the hood, look at the right side down towards the serpentine belt, that the compressor, then start car and turn your A/C to cold full blast to see if it kicks on and actually does it's job. If you do the A/C Compressor job yourself, I made an easy thread of doing it here -----> A/C Compressor Replacement.

Thanks for the replies. The system doesn’t run long enough to cool. As soon as you turn the ac on, it makes the whining sound. Clutch is trying to turn but stops after a few seconds and the light on the ac button goes from solid to blinking. Prior to this everything was working fine, ac blew cold.

Exactly what it did with mine

Bigmike,

Did you have to flush the lines - any issues with metal shavings?

Thanks for the link to the write up, had a hard time finding something similar.

Yes, I got a EVAC and Recharge from local place, you can EVAC it yourself and this video https://www.youtube.com/watch?v=Pdq8JAlct6s does a great job explaining how to do the job if you dont want to get it done by a shop. Call around and you'll be surprised at how many places to cheap Ones. Even if you find a place that will half the price of the EVAC is good because refilling refrigerant isnt all that hard. And I never ran into any metal shavings problems

ok, the compressor is toast then, mine behaved same, had a leak, and i usually topped up the refrigrant, but guess the compressor oil escaped through the leak, and it ran out of oil and siezed.
to confirm this, with the car off, try to turn the clutcth by hand, if you cant, then am 100% certain your compressor is toast.

you need to change your condenser as well if this is the case, to rule out metal shavings floating around in the system

Believe it or not, I got pretty good service from Jiffy Lube in a similar situation when my AC clutch failed. I elected to change out the compressor, but since it hadn't seized I didn't change the other parts.

The system was still full of refrigerant. I brought it in to Jiffy Lube and they evacuated the R-134 and de-pressurized the system so I could take the vehicle home and safely change the compressor. Then when I was done a few days later, I brought it back, they pulled a vacuum on it to get all the air and moisture out, and then recharged it. Total bill was $75, which I thought was reasonable. Made it safe and legal for me. The bill was actually less than a normal recharge, since they had "banked" the original refrigerant for me and didn't have to supply new.

That was six years ago and it's been working fine ever since.

Mine is behaving very similarly. Minus the squealing.

I did verify that the clutch engages and slowly spins but then stops after about 5 sec. No grinding or squealing. (Already eliminated the Relay and Pressure switch. Bypassed them all and fed power from battery terminal. Clutch engaged and slowly spun)

I CAN turn the clutch by hand. Does this mean I just need to replace the clutch? Or should I just bite the bullet and replace it all?

Sounds like it's locking up. When it does that the revolution sensor sees the lack of rotation and turns it off. This is a safety item that's on a lot of vehicles due to the fact that the serpentine belt on many cars also drives the power steering pump. So if it locked up and it didn't get turned off the belt could be burned off and you would lose power steering and on some vehicles with hydro boost, power brakes as well. Also, when the rev. sensor does that it causes the light to flash to let you know you have a problem.