Chrysler Repair: 99 300m: inadequate heating, chrysler 300m, digital temp

Question
QUESTION: Hi Roland,
I have a '99 Chrysler 300m that never really warms up. I had to replace the radiator in July but that didn't help. I have to use royal purple brand to keep it from over heating when idling in the summer (I live in Houston, TX area. It gets hot!). I got my car used '08 from southern California where the heater really wasn't needed. I freeze every morning during the winter. I takes about 45 mins of driving before it takes the edge off the cold. It doesn't get warm just not as cold. The fan turns on and off but that's it.  Can you help me? Do I need to replace the Oil Cooler?

ANSWER: Hi Dawn,
Two things to do: a calibration and a self-diagnostic test. I assume that you have the digital temp readout called an Automatic Temp Control unit.
First: start the engine, turn on the control unit, while not moving the car run it with the temp set for full coldest temp for two minutes. Then change the temp for full hot temp for 5 minutes.
Then see if that has had any impact on your problem.
If not, then set the temp to 75<sno F setting with the engine running and the car sitting still.
Simultaneously press the floor, mix, and defrost buttons (lower 4th button/upper 5th button/upper 6th button) and the diplay should start to blink. It will go through some self-tests and when done it will either read a two-digit number or it will return to the normal teme reading followed by F. Let me know it you get the trouble code number and we'll go from there.
The oil cooler, nor the radiator, have anything to do with the problem. It may be that there coolant flow through the heater core is impeded and you could check that by locating the two hoses that flow between the engine and the cabin through the firewall (behind the engine) and feeling them to see if they are about equally hot. If not let me know that too.
Roland
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QUESTION: OK, well I did the lowest to highest as suggested, no change. Did the diagnostic or self-test it blinks then it stops, no code forthcoming. I checked the hoses and both feel to be at equal temps. Is there something else or do I need to bite the bullet and take it to the shop?

Answer
Hi Dawn
Do the hoses feel quite hot to the touch or just warm? If just warm then the engine may be running too cool due to a thermostat that opens at too low a temp or is stuck open. What does the temp gauge show on the instrument cluster when you have driven it for a few miles? Ideally the hoses would feel quite hot and about equally so. Until we have that situation you will have inadequate heat.
Roland
PS If you would rate my answer I would be most appreciative.