01 Silverado Problems

[onebadbowtie]

Recently my heater/ac controls have been messing up. when i turn the temperature adjuster to cold it still blows hot air. I have tried every setting to see if i can get it to work and i got nothing. everything else works just fine though. Whats wrong with my controls? Do i need a new control unit?

Also the horn quit working recently so i checked the fuses and they are good. Next and i went to the salvage yard and got 2 working horns and put them on and they still dont work what should i check next?

Thanks James