Your 2001 e46 325i BMW heater is blowing cold?

If your 2001 e46 325i BMW heater is blowing cold air, it could be due to a few common issues. First, check the coolant level, as low coolant can prevent the heater core from warming up. Additionally, inspect the thermostat; if it's stuck open, the engine may not reach the proper operating temperature. Lastly, consider the heater control valve or clogged heater core, which could impede hot coolant flow into the heating system.