How to fix a Porsche 944 heater it's not blowing any hot air into the car and the weather is very cold?

To fix the heater in a Porsche 944 that's not blowing hot air, first check the coolant level, as low coolant can affect heating. Ensure the heater control valve is functioning properly; if it's stuck closed, it won't allow hot coolant to flow into the heater core. Inspect the heater core for clogs or leaks, and examine the blower motor to make sure it's working. If these components are functional but you're still not getting heat, consider checking the thermostat and the climate control settings.