If I've not used my AC for some time and it's been very warm out, when I first turn on my AC it sounds like a turbo blowing off pressure (or a belt slipping?). It has done this when I'm sitting still and turn it on or when I'm driving down the road. When driving it actually caused the truck to hitch a little, like the AC compressor bogged the engine down briefly.

My thought is the belt is slightly off track due to the heat and binds up a touch when it is first engaged, and the belt needs to be replaced. A buddy mentioned it could be the pully on the compressor.

The AC works and blows cool air, but I don't know if it is operating as it was when new as this is the first summer I have had the truck.

Thoughts?

 

If it squeaks when you turn the A/C on it is the belt. Inspect it and look for cracks or glazing. It is normal to feel the A/C compressor kick on when driving. Get a good quality belt and go from their.

 

It's definitely much more than just a squeak or squeal. Compare it to the sound of a big rig's air brakes - the "pffftttt!" type of a sound. That's what it does, pretty loud.

 

It sounds as if your belt has an issue. Don't know how many miles you have on the truck. Doubt it is a compressor issue. I have seen this problem before but it was 1 in 1000. My truck will have a clunk type sound every know and then when it has set for a week or so. This is normal. Just some rust buildup on the compressor clutch. All vehicles will do this. Just cycle the A/C on and off once and it will be fine. I would recommend that you run your A/C in the winter or anytime as much as possible. Lubrication is what keeps your seals in good working order. Worked on many A/C systems and compressors on Auto Air vehicles seem to last the longest because they run almost all of the time.

 

Thank you for the information. The truck has about 43k on the clock, it'd be a good idea to change the belt I'm sure anyway. I do try and run it as often as possible.

 

Like I said. Check it for glazing and cracks. I have 31,000 on my truck. Belt is getting somewhat warn. Only one belt so I will probably replace it soon and put the other one under the back seat for emergencies.

 

Spooler, you have an 04.5. Belts should last WAY longer that 31,000 miles. Many of us with the 04s and 05s had belt shredding issues (my original went at 5400 miles.)

These engines are HARD on belts - the diesel squeak at shutdown, while normal, does but stresses on the belt that a gasser does not.

 

For what its worth mine does exactly the same thing. Sounds like a compression release and only does it when first turned on. If I cycle the compressor it stops. I kind of ignored it until my wife said what was that? Makes me wonder now a little but it hasn't caused me any issues so far and the belt is in good shape.

 

Mine does the same thing. It just started recently. I have 51000 miles on my original belt. It only does this when I first turn the air on, then it doesn't do it as the compresser clutch kicks on and off.

 

Found out yesterday after the truck had sat for a few days - it's not only when the AC is on apparently. The AC was off, but the vent control was on low. I started the truck and a few seconds later the truck shuddered and I heard the air-blow-off sound again.