I pulled the AC relay and got a very small amount of barely warm air. Even on defrost there is still no warmth. I cut into the heater box behind the glove box with a dremel and can see the blend door opening and closing when I turn the control from AC to heat, but still no heat. I have looked and looked under the dash and under the hood for any type of control cable that would switch the AC to heat and I cannot find anything. Is this vacuumed controlled?????