Chrysler Repair: 01 Sebring - temperature control knob only works on high, heater coils, sebring lx

Question
Hi there,

I did a bit of searching on your answers but want to make sure I understand.  The temperature knob on my 2001 Sebring LX V-6 only works on high.  Are you suggesting that the resistor block probably needs replacing?

Also, I have had my car since 2002. I bought it with 37,000kms on it.  If I have the heat on and then need to idle because of traffic or even at a red light, the heat starts to cool down and blows cold air. But the moment I start to accelerate, it changes to hot air.  This happens even when I rev the engine while idling but once I stop revving it goes back to cold air.  This was happening even before the temp control only worked on high.  Any ideas?

Thank you,
Vicki

Answer
Hi Vicki,
Thanks for reviewing the prior questions. If by "the temperature knob...only works on high" you mean the blower fan only runs on the high setting, then yes the resistor block is in need of change.
On the question of cool down at a stop light, how does the temperature gauge on the dash appear (if there is one) to behave. If it also drops down at a stop then that may be the reason for the cool down of the heater, and so one would wonder about the thermostat on the engine being open at too low a temperature. On the other hand, if the engine temp gauge stays pretty well about 1/4 scale then that is not the issue. Rather it is a question of whether the hot water is flowing consistently thru the heater or whether the the temperature door which sends air variably across the heater coils or the A/C coils to control the temperature of the final air that enters the cabin is not behaving properly. I unfortunately don't know whether in the stardard heating system of the Sebring that door is mechanically controlled by a cable (in which case it shouldn't move by itself) or by an electrical motor (particularly if you have the automatic temp control unit with the digital temp readout dial) or possibly by a vacuum operated actuator (and if there was a vacuum leak then the door might move due to the difference in vacuum related to idling vs. accelerating or cruising along). So I guess this is not much help because of my uncertainty.
What you could do is observe the temp gauge on the dash and also you could look behind the engine at the firewall (panel between the engine compartment and the cabin) and try to locate to 3/4" hoses that go from the engine thru that wall to the heater in the cabin. Then with the engine idling see if the hoses feel equally hot which would verify that the hot water was going into and back from the heater core. And secondly, in the same general area see if there is a very thin plastic or rubber tube that similarly goes thru the wall and would mean that vacuum is part of the controls. In that case, check whether the end of that tube is connected to a large hose near the master brake cylinder's vacuum chamber (larger round metal can near the firewall just in front of the driver). If you had such a vacuum line and it was cracked or loose that would explain why the temp varies the way it is. If you don't find such a line then it must be electrically controlled door or a mechanical control door.
So let me know what you determine.
Roland