Hello peeps, so I have scoured this sub forum on this topic, and found nothing about improving the subpar temp. coming out of my vents. At 85 deg setting with blower fan close to max/ AUTO OFF, and engine at normal operating temp, I can only get a reading of 122 deg f. Double checked my upper and lower rad, and heater core hoses, and tsat temp with live data, AND all pass with specified temp . My wagon, 4 cyl has 149k miles. Flushed coolant back in July 2020, No problem with overheating or whatnot, BUT the insufficient heat. SO, I flushed the heater core the same procedure as the 2012-14 HONDA CRV recall, and gained about 25 deg on both center vents. I didn't flush it for 1.5 hrs though, instead I let the CLR soak in the heater core for like 25 minutes, then pumped it for 30 min each side of the heater core, and recycled fresh hot tap water for 3o min. Then flushed with garden hose for 3 minutes each side until clear water was coming out. JUST BE careful in taking out the heater core hoses as it's getting cold now in Northeastern part of the US. I used a heat gun to soften up the hoses. When it came out, the pipes are made of soft alloy. Spraying silicone will help to put whatever hoses you choose to use. 5/8 is the ID size. Good luck to all who want to do this. Give yourself about 3.5 hrs overall to complete this job.

 

BTW, don't follow the half ass job that this guy did on flushing it with tap water, keep your hoses connected, and just reverse the operation from your source, and drain hoses. With our 2nd gen cars having the electrical connector with our EPS, I put a plastic trashbag on top of the steering rack to protect it from getting wet.