So a few weeks ago I replaced my thermostat with an ecobee3 smart thermostat. In the process of wiring the thermostat I blew the 3A fuse up in the attic and had to replace the fuse. The thermostat then worked fine for about a week. I do have a C wire.
Then suddenly there was no power to the thermostat. I went back up in the attic and even though the fuse looked ok, I replaced it again anyway and the ecobee lit up right away and worked for another week. At the time I suspected I might not have fully locked the cover panel in place and the kill switch might have just popped open.
Today the thermostat was dead again. I went up in the attic and the fuse was ok but I replaced it anyway. No dice. I tested the fuses from this week and last week with a multimeter and they test just fine. Still, I replaced the fuse yet again but still no power. So I don't think it's a fuse problem.
I verified there is 110v to the power outlet up in the attic where the furnace is plugged in. I used a multimeter to test the thermostat wiring for the ecobee and it appears that no power is making down to the thermostat.
I tried pushing on the kill switch while the unit is plugged in and while doing that no lights go on inside the furnace (I read online a light should go on showing the transformer is working) and the thermostat wiring gets no power on the multimeter. There's only one little red light on the control board but it stays dark no matter what I try.
Does this sound like the transformer would be bad? I can't figure out why the ecobee3 would work for a week and then die, only to work again for another week when all I did was open and close the panels in the furnace (and replace fuses that didn't need replacing).
See pics attached -- is it time to call a professional? I don't feel comfortable replacing a transformer on my own.