Chrysler Repair: No heat from Heater, heater control valve, coolant temp

Question
My daughters 2000 Stratus (2.4) recently had the heater go cold.  I got to look at it this past weekend and the coolant was very rusty in color.  Since I was 100 miles from home and did not have all I needed, I changed the thermostat and cap and then took it to a shop and had them flush the system and refill. I noticed in one of your PAQ's there is a specific proceedure for the 4 Cyl models to prevent capture of air in the Heater core.  I suspect this may be the problem because the heater is no better, just cold air.  
When I first checked it, the level was down about 1 3/4 litre (used a 2 litre coke bottle to fill!).  I would prefer to approach the trapped air problem first.  What is the proceedure and if that is not the cause, what other scenarios could be causing the problem. If any require removing the dash(perish the thought), where can I get some good insturctions of the removal process.  

Answer
Hi Bill,
Interesting that you should ask about the trapped air issue with the 4 cyl engines. The PAQ dealt with the '80's and early 90's 2.2 and 2.5L engines. I thought that it was unique to that block but then just discovered a similar issue may be involved with the 2.4L. I have a discrepency between the '96 Stratus manual and '96-99 van manual (Haynes). It depends upon whether the coolant temp sensor is mounted vertically on the top of the water outlet connector (to the right of the thermostat) or if it is mounted horizontally to the front of the cylinder head in the same general area.
If the former, then you do need to refill with the sensor removed until the level rises to the hole for the sensor, then replace the sensor then continue the fill. Otherwise with the horizontal the point is moot.
In general, the possibility of air trapped in the heater core is relevant too. The way to avoid this is to always drain and refill the system with the heater control valve open, so if you didn't do that, it is a good idea to redo the drain and refill.
To do it:
Start the engine and after about a minute move the heater control to full heat position. This actuates a vacuum operated water valve to open. Then turn off the engine.
Then start the drain procedure via the radiator drain plug. Note that the overflow bottle should empty first which checks that the system is air tight. Then remove the radiator cap for the balance of the drain. As the system is draining remove the coolant temp sensor if it is vertically mounted as described above (slowly in case the system has drained to a level below the sensor). At that point you can stop the drain procedure. Close the drain valve.
Start refilling through the radiator cap until the level fills the housing that the sensor fits into. Reinstall the sensor at that full housing condition. Then you can refill the system the rest of the way to the filler cap. Put on the cap, then fill the overflow bottle to the max line.
That should refill the system without air pockets.
One thing you might want to do first is to make sure that you don't have an internal air handling problem with the heater unit in the cabin. See if both heater hoses are hot when you are trying to get heat. If one hose is hot and the other nocticably cooler then you don't have good flow thru the radiator maybe due to trapped air, maybe due to obstructed flow thru the radiator. So in case of crud, you could disconnect the hoses and reverse flush the heater core with a garden hose. Then do the drain and refill. If both hoses are similarly hot, then it is possible that the air control door(s) are malfunctioning and not sending air over the heater coil unit.
Let me know what you find out.
Roland