I just drove my truck over the weekend for the first real time (been in the shop since i got it, few appearance mods and a wetsand/detail) and i must say I love it.(got better gas mileage then my v6 gp) I just have a few questions regarding the truck.
I noticed that when I slow down from anything above 65mph, then speed up again the truck seems much louder. Is this common or something I should worry about?
Also the airconditioning will occasionally just blow out hot air...It usually wont last for more then 15seconds to a min..the first time I drove it howver it took about 10mins to get cold. I heard (cant remember where) that the ACs on this truck werent the best;) ...Does this mean I will need to replace the AC in the near future?

Thanks.

Since it's an '03, you bought used. Mileage?

As to the noise upon speeding up, is it engine noise? Is there a tranny shift in there?
I notice the same thing at much lower speeds, but this is due to a transmission shift to a lower gear.

Air conditioning....
There are four (4) radiators on the front of these trucks, 3 if you have a manual tranny.
From front to back they are:
Transmission cooler
Air Conditioner condensor
Charged Air Cooler (turbo intercooler)
Engine coolant radiator.
These four radiators are often called "the stack".

Read the many treads about overheating in the LLY engines. KillerBee* (and several others) have put in a lot of work studying this problem, and it looks like they have found the root-cause. There is apparently an air-flow issue with these trucks, most especially with the newer versions.
Most (or all) of these overheating issues can be fixed by "sealing the stack" of these radiators to make sure there is sufficient cool air flowing through the stack, and not around it.

Barring other problems with the air conditioning system, sealing the stack will improve its performance.

I have an LB7 '04, and have never had problems with the A/C or with overheating. There are times I'd like the A/C to be colder, though that is normal on 100 degree days here in Texas.

* Thanks to KillerBee & all you who have put work into solving the overheat issue. I'm amazed that GM isn't on top of this and didn't solve it as fast as you guys did.

yea, my dad is a used car dealer so ill probably never end up gettting a new vehicle. We purchased it last week with 77k miles. the noise it makes kind of sounds like an intake noise?? like a big wooosh..
Also, I have to press eject like 6 times before the cd player ejects the cd...it just makes a ticking noise then says "check cd"..its pretty annoying..probably have to replace that real soon

bump.

yea, my dad is a used car dealer so ill probably never end up gettting a new vehicle. We purchased it last week with 77k miles. the noise it makes kind of sounds like an intake noise?? like a big wooosh..
Also, I have to press eject like 6 times before the cd player ejects the cd...it just makes a ticking noise then says "check cd"..its pretty annoying..probably have to replace that real soon

The noise it makes is probably the turbo. If your new to diesel's you might not be used to the turbo spooling. The AC problem might just be your system needing a recharge.

The AC problem might just be your system needing a recharge.

In my case the AC was a little overcharged, they replaced the low pressure switch, and lowered the AC charge according to a TSB. The AC works but nothing like my wifes 03 Tahoe.