I fixed my PBU last week by reflowing all the connections inside. It is a reman unit and I assume that means they have gone over all the copper traces with solder as that was what looked like was done. I just reheated all the pins where they came through the boards, and then went over all the traces for good measure. This fixed many issues I had with heat and defrost. Lower vents now open for the heat, fan runs at whatever setting I put it on, and I have heat when I want it.