The dealer just wants to make money, the compressor clutch cost upwards of a $100.00 the compressor will have to be removed to make this repair. With the a/c switched on check the voltage going to the coil which will be the only wire going to the a/c compressor and see if you have 12volts if so have some one switch the a/c switch of and on and listen for a click if not the coil is burnt out that pulls in the clutch that turns the compressor. The dealer does sell the coil but rather sell you the compressor complete
I worked in a parts store for five years. When the clutch goes bad its always a good idea to replace both . The compressor goes out soon after. I also have an 03 sorento and did both. U can find the complete assembly with drier for about 245 at discountacparts.com. Free shipping I was satisfied. Even tho I hate my car it breaks down all the time. If the clutch isnt engaging and you have power to ur plug on compressor than just replace both. If no power theres about 3 or 4 relays in the relay box under hood and some breaker fuses to check.