Originally Posted by Cusser

Do you mean the refrigerant hose in the engine compartment? These should be straightforward to replace, but first the refrigerant needs to be removed and (legally) collected. The hose itself will either connect using new O-rings (lubricate them with refrigeration oil) or flare fittings. then vacuum MUST be pulled and the CORRECT amount of R134a put back in. I'm not sure the dealer diagnosis is correct, i'd take to an AC auto specialty shop myself. I can see a hose leaking or not leaking, and obviously a leaking hose could cause low refrigerant level and your symptoms. You should be able to see the leaky area by a buildup of oily residue.