Why doesn't my new truck's a/c blow as cold as my old one?

[oldbustedchevy]

I bought a brand new 2010 GMC Sierra to replace my old 1992 Chevy Silverado. Both are just base model single cab trucks I use for my lawn business. Well using a thermometer, the 92 blows 10 degrees colder than the new one does. I took the truck to the dealer and complained, but they said everything is working properly. The 92 blows 35 degrees, and the 2010 blows 45 degrees. Anyone know why the newer models are like this, or if I just bought a crappy truck.