Does the H relay ever pick when it tries to run? If not, maybe the H Triac. If it does, RH is at address 0E97. If RH isn’t going high with H picked, follow the input up through the ribbon cables and see where you’re losing it. If it’s 120 vac, it will step down to 5vac after the big resistor before it gets to the ribbon cable. I’m not sure though, I don’t have print for an A17.1 - 2000 controller.
