I just installed a non a/c heater box in to my car that use to be an a/c car and I am confused on the wiring for the resistor the new one has three prongs the old has four. Does any one how I should rewire it or should I try to find a four prong resistor.

Thanks for your help

 

Just put your old resistor in the new box.

 

thanks for the respons I figured that but was not shure. I did a test fit with the three prong resistor and it only would run on high, would the old resistor give me low medium and high?

 

yep, that's what the resistor is for, to control the blower speed. without any resistance at all, the motor runs at full speed.