I just bought an 03 Optima and the blower motor ran on hi no matter what speed i set it at. i looked all over the internet for answers but couldn't find anything that matched thenpart I had. the replacement resistor had 4 prongs and my part only had three. well what I found out was that the cars with the digital hvac systems have a different part. it is actually called a transistor. they wanted $150 bucks at the dealer. I found one at a salvage yard in a Hyundia XG300. it cost me 20 bucks and now my fan controls work. just wantedto relay this find to anyone who is having trouble findingthis part. the part stores don't carrythe three prong part.