Since the weather turned cold here, I started to feel the heater isn't as strong as it used to be, it's still warm especially if I crank the temperature up to like 80 degrees or above, but if I let it stay at 72, I don't feel much heat, I don't feel cold though, so I am exactly sure whether that's the way it's supposed to be because I am at Mid Atlanta, and the weather here is mild.

I read a little bit on the internet last night, and everything looked fine. The coolant was full, the car has no other issues and the engine warms up properly. One thing I noticed that though was the inlet temperature to the heater core was around 137-138, while the return pipe was measured at 105'ish, and was actually lower when the heater was cranked to high which I think is reasonable since in the "high" mode, the heater was consuming more heat. Under the "high" mode, it was fairly warm, although I am not sure whether it was as warm as it was - I guess I rarely needed that mode. From what I read, the two pipes should have about the same temperature. If not, it means either the heater core is restricted/plugged or the valve isn't fully open. These pipes are hard to get to, so I don't plan to try to reverse flush it myself.

I wonder whether someone can measure theirs, and see whether the numbers are different. I have 70K miles on it, and about exactly six years from the day of purchase. I only did one flush at the dealership when it was at about 38K miles. Should I try to send it in to have the cooling system flushed?

Thank you all in advance.

 

What's the outside temp when you say "if I let it stay at 72, I don't feel much heat, I don't feel cold though"? If it's 40s to mid 50s, and the car has been sitting unused for a couple hours then you should feel heat. But if it's upper 50s - 60s then the interior temp of the car is likely close enough to 72 that the system senses that and doesn't put out max heat.

 

I used Auto Climate Control best in Summer. In winter, it's best to not use it. I would crankk up heat to a higher temperature to confirm that it's working correctly.