I have a 2009 300 Touring. I have an issue with lukewarm air blowing out no matter what temperature I set the controls; the temperature is around 70 degrees when set to the highest setting. It's been 20 degrees here so I have not been able to diagnose the problem. But that hasn't stopped me from thinking. Someone in another post (a few years ago) had mentioned the engine oil cooler. When looking at the engine oil cooler, would the temperature of the inlet and outlet hose signify anything? Also, what about the heater core valve? Is that another component to take a look at? If so, where is the heater core valve located? Or is it the same as checking the temperatures of the inlet and output hoses to the heater core? Just trying to understand the whole heating system.

Thank you.

 

warm the engine up then put your hand on the two heater core hoses going into the fire wall both should be hot enough your cant hold them for more then a few seconds. let me know if they are both equally hot or not hot or luke warm.

 

So, this morning, I did some testing and took temperature readings. I drove the car for about 45 minutes and then came home to take some readings. Note that during the time I was driving, the fan setting was set to Auto, temp setting was 78°, and the vent control was also set to Auto. The car's windows were fogging up all around; this is because the cabin wasn't warm enough. I guess my final results (after the car running for an hour) are normal? Is it normal for the temp coming out of the vents near your legs to drop so much?

I normally do not drive the car for more than 45 minutes at a time during the day. So maybe I never noticed that the car takes an hour to get to the proper temperature.

After the car was driven 45 minutes and sat running in the driveway for another 15 minutes, here are the results.
Upper hose going from engine to radiator: 161°
Hose going to heater core: 130°
Hose coming out from heater core: 106°

Legs: heat set to HI and blowing LOW, temp rises to 135°
Legs: heat set to HI and blowing MEDIUM, temp rises to 102°
Legs: heat set to HI and blowing HI, temp lowers to 85°

Face: Heat set to HI and fan blowing LOW, temp rises to 145°
Face: Heat set to HI and fan blowing medium, temp drops to 131°
Face: Heat set to HI and fan blowing HI, temp drops to 125°

 

whats the lower radiator hose temp?