I have a Trane XL1200 Heat Pump that was disconnected and reconnected due to some foundation work this past July. The contractor picked the company to do this work and the tech miss-wired the low voltage line between the Heat Pump and the Air Handler. The cooling function worked fine and we did not notice a problem with the defrost cycle until the outdoor temps fell into the teens. It would not initiate a defrost cycle. I called the same tech back thinking it could be a problem related to his work and I was right. He ordered the DFC board, which did not fix the problem. I think he knew he had mucked up the wiring and left to order a second DFC board and never came back or called. After much work on my part I believe I have corrected the LV wiring. My question is this: There is an LED on the defrost control board (CNT02515). Should this light flash once per second as soon as power is applied to the outdoor unit or should it only flash when the compressor is running. Thanks for any help.