Arrived on site to diagnose a no cooling unit. Client stated he moved in 5 years ago and he’s been having the unit shut off every other year so thought it was a fuse. Tried to cycled down stairs nothing. Client has a home alarm system that he has his thermostat connected to and that’s how he controls it all from his phone. Found nothing was operational at the home alarms system. He did have a separate thermostat. Found batteries low. Advised he needs them replaced. Jumped in attic inspected electrical compartment. Found power was there and just just in normal Stand by. Inspected thermostat on wall. Found low voltage fuse as going to thermostat. Found thermostat on wall was not operating properly. Jump Ac on from the thermostat wires at the wall and unit was operational. Tried to turn on from alarm systems and still did not work. Advised him his issues is there thermostat on wall is not working. So home alarm system is not controlling the thermostat on was since it’s bad. Showed c