BMW Repair: Intermittent heal, heater coils, radiator heating

Question
1997 325i  Both sides blow cold air when car is stationary.  Drive down road and heat gradually builds to normal.  Stop car and blows cold again.  

Answer
Hi Kenneth,
First of all, you should check if there is air in the cooling/radiator/heating system. Remove radiator cap, remove bleeder screw, top off coolant/water until it flows thru bleeder screw, then close screw. Run engine to approximately 1500 rpm and top off coolant again then close radiator cap.
Once you are sure that there is no more air inside the system:
Either there is no heated water going to the heater coils or even if there is heated water, the valves controlling the flow of blower air into the heater core is not working properly.
The heated water going to the heater coils is controlled by the water valve(on left rear side of engine compartment, this is the part with 2 cylindrical protrusions on top and connected to 2 hoses, one of which goes to the evaporator/heater), and the water valve is switched on by the  manual switches or the automatic switch/control module.
It can be that the water valves are bad, or the switches, or in some instances, a bad AUC sensor or bad ambient temp sensor (the former is at the top right side of the radiator and the latter is below the front bumper in the left or right airduct area).
Check your dashboard temp reading, and if it does not seem
relevant to actual current temperature, then replace the temp sensor.
Check also the water valve if it is being powered up or switched on when you turn the heater on.If there is no 12 volts switching the valves, then the switch (manual or automatic is not working). If there is power but the water valve does not work, then the valve is bad. While I do not recommend it, it is but logical that if the engine is running and the water valve is working, then  you can see if water would flow from the hose of the valve going to the evaporator/heater coil.
The AUC can only be diagnosed with a bmw scanner since OBD scanners would normally not be able to do so.
As always, a scan tool's readings would be preferred though not necessary.
Update me of your findings.
Tino