Heater Not Working E39 2004 530D

[CLIFFL]

Temperature is steady and normal, blower works fine but no heat is coming out at all.
I have noticed over a long period of time its been getting worse.

Regards Cliff

[crankedup]

Broken sensor, air lock perhaps.

[helix402]

Check coolant level.

[njw1]

The heater valves which are mounted on the passenger side inner wing could be stuck shut, when the car is up to temperature very carefully feel the pipes coming out of the valves, they should be hot. Other than that, have you added any radweld or k-seal type stuff to the coolant? A previous owner put something in my car (an e39) which seemed to clog the heater matrix. I've flushed it through which has brought some of the heat back but they're still not as hot as they should be.