The noise on acceleration- change the AC belt first and see if that's it.
The rest of your problem sounds like a blockage in the low pressure line. Very common, a shop can evacuate the entire system with a vacuum and re-fill.

 

The noise on acceleration- change the AC belt first and see if that's it.
The rest of your problem sounds like a blockage in the low pressure line. Very common, a shop can evacuate the entire system with a vacuum and re-fill.

Thanks for the feedback. I have been experimenting over the last week since the last time it happened. Basically, I just haven't turned the AC switch off for the past week and it has stayed nice and cold the whole time.

Is there a vacuum operated switch in it or something? I ask because sometimes, with the AC switched on, when I start the truck I hear what sounds like a vacuum operated door actuating. Makes me wonder if there is a vacuum leak of some kind.

As for the whistle...I'm due to replace the belt anyway but it really doesn't sound like a belt noise. Guess we shall soon see if a new belt helps.

Thanks again!

 

I did have a couple more episodes of my AC taking a long time to cool down even without switching it off so I put a gage on it and found it was low on Freon. So I got some EZ Chill and topped it off. Going to be really hot around these parts this coming week so I should get to test it pretty rigorously.

 

I had the same issue the past couple of weeks. A/C worked fine but made a whistling noise (like someone playing a single note on a flute) when accelerating from a stop. Then I found that I could re-create the noise by just holding the RPMs around 1500 in park, whistling was most noticed coming threw the center dash vents. Then today it started blowing fog (no odor) out of the vents. Had the A/C checked and it was slightly low on freon. My mechanic evacuated the system and refilled. Problem is gone!

 

That's really good to know, Narda! Sounds like the exact issue. I have been trying to avoid getting the shop involved so I just added the freon myself. So far it has been working good with no fog coming out but do have the whistle occasionally. I was conservative when I added so this weekend I will put the gage on again and see if I can add a bit more. Already have the shop scheduled to do my brakes this weekend so I didn't want to add any expense with the AC if I can avoid it but I suspect your way is the better way.

 

Well, I checked it again and it was still slightly on the low side. Put in the rest of the can of EZ Chill and now no more whistle and it's so cold I had to adjust the temp knob warmer even with the fan on low.

 

There must be a leak in he system, It won't fix itself.

 

There must be a leak in he system, It won't fix itself.

Perhaps. I understand it is not entirely unusual for a 10 year old truck to be a bit low just from normal use. EZ Chill contains a sealant so we'll just see what happens from here.

 

May as well kiss your system goodbye then. I never use, nor would recommend any of that parts store recharge with a "sealant" in it.

Only way to truly fix a leak is it first find it (obviously). Can use dye that's made for your specific refrigerant and see where the dye is coming out. Can also use nitrogen and soapy water if it's a larger leak.

On older systems I usually find the evaporator and condenser are common areas to leak. As well as the orings at the fittings

 

May as well kiss your system goodbye then. I never use, nor would recommend any of that parts store recharge with a "sealant" in it.

Yea...sure. It's a 10 year old truck. Probably just normal leakage over time, but if not, and the system eventually craps out, then it will just be a truck with broken AC. But in any case...EZ Chill is the perfect product for my truck and situation right now and I will bet it will get me through what remains of our Minnesota summer just fine.

 

Will probably get through summer. And who knows, maybe it will last.

But the stop leak stuff ruins compressors. I've had several where that stuff was used and the compressors get all nasty and gummed up inside, and end up seizing.

Not much different than how the cooling system stop leak products ruin your cooling system.

Should be considered a last ditch, I no longer care about this vehicle, type of thing. Of course that's just my opinion based on what I've seem come into the dealer.

 

I have to agree with 19trax95 as far as using a refrigerant that has some sealer in it. It may clog your orifice tube filter on the low pressure side of your system over time.

It's similar to adding a radiator leak additive that will clog the whole system.

Good luck with what you added and hope it works a long time. Otherwise the system will need to be flushed completely and a new orifice filter installed. If your lucky the compressor will not have accumulated any of that sealant and messed it up.

 

in my case my system was only down about 2 tenths of a pound. My mechanic was surprised that such a small amount caused the issue.

 

in my case my system was only down about 2 tenths of a pound. My mechanic was surprised that such a small amount caused the issue.

Indeed.

 

The real irony for me is that it turns out the best repair I made was fixing my window switch panel. The weather's been so nice here in MN I really haven't used the A/C much but sure is nice being able to put both windows down!

 

My whistling came back the other day, a further check of the system revealed a pinhole leak in the condenser. I have an extended warranty that covered the repair, the agent at the warranty company stated that this is a common problem and they replace a lot of condensers on Silverado/Sierras.

 

I'm not under any warranty at this point, but I'm glad you shared your experience here. If my whistle comes back it gives me something I can check. So far, mine is still working great, but I haven't been using it that much due to the cooler than normal temps we've been having. Another few weeks and it will be off until next year.

 

Just an update. Today is an unusually warm December day here in Minneapolis so I turned on my AC (as I often try to do once or twice during the winter season just to get everything moving a bit). Still working perfectly. No noises, no fog, and got really,really cold just like it should.