I am restoring a 72 cutlass s that was half missing when I bought it, i put a new core in and just got a ac delete cover but I don't have any relays, blower motor, or motor resistor. My question is how do I make this work with the factory heater control in the dash. Do I get a resistor and relay for an ac system or just heat or do I have to change the dash unit to one just for heat.