The answer to 'furnace repair not cooling' is that there are several common causes, including a dirty air filter, a malfunctioning thermostat, or a refrigerant leak. Symptoms may include the furnace running but not producing cold air, or the air coming out feeling warm instead of cool.
Some solutions you can try yourself include replacing the air filter and checking the thermostat settings. However, if the issue is a refrigerant leak or a more complex problem, it's best to call in a professional HVAC technician to diagnose and repair the issue properly. Attempting DIY furnace repairs can be dangerous and may even void the warranty, so it's important to know when to call in an expert.