Came out to call. Customer said she had someone out to fix the wiring she accidentally cut with the mower. The system still wasn’t working properly. I checked system over and found the furnace is from 83, and has a fan relay transformer combo. I had power to the transformer but not 24 volts. OG&E thermostat wasn’t operating, and went blank after I checked wiring. I do not have this part available and need to pick up from a supply house. Told customer I’d get one tomorrow and come back to put it in. 07JUL20-Installed the transformer/relay combo. Wired it in and the thermostat went blank. Installed a new discounted thermostat. I found there was a loose wire behind the relay. I retightened all the wire nuts. Tested the system in heat, fan and AC. All working properly.