I was called to diagnose a Carrier furnace that was not producing heat. I arrived at the customer's home and performed a series of tests to determine the issue. I checked the thermostat, the furnace, and the air filters. I also checked the electrical connections and the gas line. After a thorough inspection, I determined that the furnace was not producing heat because the gas valve was not opening. I replaced the gas valve and tested the furnace again. The furnace started producing heat and the customer was happy.
