Low heat output

[bpolly2004]

2009 ram 1500 5.7
A little bit of history. Last fall I replaced my heater core, and evap core behind the dash. This past spring I had to pull dash again for a failed blend door actuator. Last fall I had great heat in the truck. Like 150 degree heat from the vents. Fast forward to this week I have run into low heat output again. My vent temps were in the mid 90s so I did heater core flush. Temps from the vents went back up to 120 on driver side and 135 on passenger side.

Today I have low heat output again. 73 in drivers side vent and 115 on the passenger side vent. I have checked the antifreeze level and it's good. I have recalibrated the climate controls which moves all the blend doors back to normal positions. I have my climate controls set to hi /hi with air coming from main vents. What else should I check? I was thinking I may have inadvertently crossed connections at the heater core but when I traced the line back the top hose goes into the inlet tube on the motor. Which I was told is correct. Any ideas?


Temps today got in the low 20s

 

[crash68]

I know people will ask, what's the coolant temperature showing? Are the heater hoses getting hot?

 

[mtofell]

I just went through the whole low-heat thing and a flush worked but the getting all the air out of the system does seem to be kind of a PITA. I've been cracking the coolant fill reservoir once a day or so and often get a "burp" and the coolant level changes. This doesn't seem to be affecting my heat output but you might be sure you have all the air out.

 

[bpolly2004]

I know people will ask, what's the coolant temperature showing? Are the heater hoses getting hot?

Yes both get hot