Pontiac Repair: HEATER FAN, grand prix gtp, heater fan

Question
i have just bought a 1998 grand prix GTP and it came with no heater fan so we got a new one and hooked up and than it didn't work so we went and got a new one and hooked it up and it still didnt work and than i took it out and took and ran it right off the batt and it worked fine and than i tested the wire and it had full power the whole time even when the keys were out of it.what can i do to fix it or what is going on with my car  

Answer
Hi Christopher:

I assume that this car has auto climate control control? If so that has a blower motor control module that runs the fan. It whas constant power from the control module and the module varrys the amount of ground going to the motor. It can be eithet the control module is bad or the heater control module is not commanding the blower motor control module on. It' like 90% chnace for the blowr module and 10% it's the heater control head.
Good luck :)