A/C worked fine, fan worked, no heat. I was pretty scared that I was looking at $20,000 for a new HVAC system. After going though some online videos my wife called in an HVAC person to look at it. Turned out I had a very obsolete control module that went out, but was lucky enough that they had one lying around in one of their trucks. It was an expensive bugger (because it is obsolete), but $900 is MUCH better than $20,000.

I recommend hitting YouTube for ideas specific to your brand/model of furnace where I found some great troubleshooting tips from retired HVAC guys. Glad I hired it out though because he found a couple of other parts that needed to be replaced. If you are in Utah Valley I recommend Gunther's in AF.