BMW: BMW 740iL, water temp gauge, coolant level

Question
My 1995 740il heating system is flaky.  No heat when the setting on the console is turned up and the fan switches on.  Sometimes, at speed (65 mph or so) the heat will come on intermittently.  No heat at all at other times.

The coolant is up to the proper level.  Water temperature gauge shows the coolant to be in normal range when driving.  Could it be the air filters?

I have not checked the thermostat -- but the water temp gauge shows the coolant is kept in the normal range when driving.

Thanks.

Answer
In my opinion it is one of 2 things, the heater core unit is bad or the actual controls are not actuating.  Do you have digital or analog heater controls... The analog ones run a cable that mechanically opens and closes the unit.  I would check that.  Also if your car is maintaining a proper coolant level and your temp needle is showing proper temp readings more then likely your thermostat is good. hope this helps...