I have a 72 dart 318 that was originally an A/C car. I removed all of the A/C components from under the hood but left everything under the dash and I am using the original stock control buttons. I am getting heat through the vents under the dash and all three speeds of the blower motor appear to be working. However, when I hit the defrost button the hot air continues to come out of the vents under the dash and not the vents on top of the dash by the windshield. Lastly when I press the Max A/C button the amount of air coming out of the vents (still hot) is much stonger than when the Heat button is pressed. Any help with the defrost would be greatly appreciated.