I have been going through a few HVAC problems recently. 2 months ago my Circuit board in the unit underneath the house was damaged and had to be replaced. Not cheap, but it was fixed and it ran great till last week. We had the unit on heat, and it had been for at east a week, so it was not the transition. The new Circuit board blew the 5 amp low volt fuse on. I replaced it and it blew it immediately. So I replaced it again, and noticed that before the fuse would blow, the system would buzz for 2 to 3 seconds. So I call a HVAC and they tell me that the board that had ben working properly for 2 months is bad, I'm like hummm.........So I pull the board and began checking everything. The board seems fine so I continue on my quest. I begin hooking th board back up 1 wire at a time and find the culprit to why the fuse is bing blown. When I plug up the 4 pin (wire) connector to the board is when the fuse blows and only then. The only problem, I don't know what these four wire go to? I believe they go to the heater coils??? There are 2 black wires, 1 yellow wire and 1 purple wire in the connector. As said earlier, every wire on the board can be hooked up but as soon as this is connected, bzzz and the fuse blows! HELP ME PLEASE!
Below are some pictures, If anyone can help, I would appreciate, I am just looking for my problem!