Chrysler Repair: Heater not putting out enough, blows only on high, yiy, heater core

Question
I have a 1999 Sebring. First it was overheating and I changed the theromstat. Now the heater will work for a little bit then stop heating.  The temp is about half way between cold and hot.  The heater also only works on high. I have coolant but in the over flow it's full.

Answer
Hi Joni,
The temp problem with the heater output probably is due to air trapped in the heater core. You could evaluate this by feeling the two hoses that run through the firewall to the heater. After you have the engine warmed up and the heater selected both hoses should feel quite warm. If one is significantly cooler then there is not good flow due to trapped air. What you need to do is drain off and coolect some of the coolant to below the level of the heater core, but this time you want to first start the engine and turn on the heater, then shut off the engine, then start the draining process. That way the heater core valve will be open so that when you refill it coolant will flow into the core and you won't have air trapped when you refill it. You will need a 19mm socket with 3/8" drive and 3" extension to open the draincock on the bottom of the radiator. If someone else did the thermostat exchange then take the car back to them and let them do this partial drain and refill procedure at no cost, because they should have done it that way to begin with. But make sure they begin by running the engine with the heater 'on' first, then shut off the engine, then partial drain/coolect, then refill.
On the blower only running on high:This is caused by the failure of a small component called the resistor block. It is located under the dash on the HVAC housing's underside next to the blower motor (right hand end of the unit). You can replace it yourself by removing fasteners that hold in place the lower edge of the dash on that right side si yiy can see and access the underside of the blower box. Then notice the wires, two twisted together coming from the round housing which is the blower. Those wires are plugged into the resistor block. The block also has a multi-wire plug. Remove both the plugs, then notice two screws on either end of the block, again facing up. Remove those screws and the block will drop out of the air duct into which it is mounted. Get a new one from a dealer for around $25 and carefully separate the resistors so they aren't touching one another when you insert it in the duct. Then reverse the steps.
Those to services should restore the heat and the multiple blower speeds.
Roland