Is your car blowing too warm or too cold? The thermostat may not be working properly.
The thermostat is part of the cooling system and regulates the temperature of the coolant in the engine. It is normally a metal valve with a built in temperature sensor. It is most common to replace it if the engine is overheating, the heater isn’t working or the check engine light is on. It is also recommended to replace the thermostat if there is any major work performed on the coolant system.