Ok I completed the blend door install. Before I put the dash back together again, I turned on the hyacinth and watched the motor and arm move. Put the dash together and now the unit works....except now instead of freezing cold air blowing when I select heat, I have cool/ Luke warm heat. Could it be my thermostat? My temp gauge is always dead center o slightly lowerq. I haven't flushed my radiator. Yet and I know that coolant is very old. I have had to add coolant and water to the system before. So anybody with any suggestions as to what the problem could be? Also how many bottles of antifreeze does it take to refill the system if I do flush it?