The answer to 'why is my thermostat not cooling' is that there are several common causes, including a thermostat issue, problems with the HVAC system, or issues with the power supply. Symptoms may include the air conditioner not turning on, the house not cooling, or the thermostat display not working properly.
Some possible solutions include checking the thermostat settings, inspecting the air filters, and ensuring the HVAC system is receiving power. If the issue persists, it's best to call in a professional HVAC technician to diagnose and repair the problem.