I have a 2002 Passat Wagon. The heater never really cranks out the heat. The engine get’s upto temp and there’s plenty of coolent in the system. Could this be a thermostat thing? Anything else?
If the engine goes upo to temperature, you do not have a thermostat problem. You could have a problem with your heater core plugged, the air door stuck in the fresh air position, a blower problem or something else. Go to a reputable shop, and they will diagnose in about 10 minutes what the actual prolem is.