Residential service call in Richardson & found the Icomfort thermostat blank and would not boot up. Checked equipment and found that system can operate with a regular thermostat. Found that the wire going to the thermostat is only a four wire and with system having two stages of heat and cooling thermostat needs 7 wires to get full functionality of equipment. Timothy approved replacing thermostat wire but I didn’t have any on the truck. Will need to return to install thermostat wiring. Temporarily set up thermostat and equipment to run 1st & 2nd stage cooling only. Checked outdoor units pressures and amp draws and capacitor all look good. System did have a hard start on it, disconnected hard start due to it will mess up 1st stage on compressor. System is cooling at this time.