2004 4Runner heater issue

Long time Toyota owner, first forum post. My son has 04 4Runner SR5 with heat issue we can’t figure out. We recently replaced the blend door actuator motor as it wasn’t moving from floor to defrost and so on. Tough job but we got it done. Next day, his car isn’t heating up. His car had been heating fine, blend doors just weren’t functioning. Checked temp control actuator located below blend door actuator and it wasn’t moving. It was moving when we replaced blend door motor the night before. Tinkered with heater fuse under hood and actuator is moving now when raising or lowering heat but still no heat. Maybe a very little heat change but hard to detect. Glove box is still off so we can see the actuator moving as we adjust heat up and down and it appears to have a nice range of motion. Checked heater core lines under hood and both in and return lines are getting nice and hot. I can change the temp actuator but it’s moving so not sure where to go from here. I’ve read where some flush the heater core but would that be the next move if both in and return lines are nice and hot? Trying to help get my 21 year old son over the hump here as we always just fixed our stuff when we were young! Lol! Input appreciated!

 

You probably already figured this out but there's a thermistor that controls the temp just to the right of the steering wheel on the lower fascia. You'll see several cut lines in the plastic. To get to it, remove the lower fascia and check the connection and tube that connect to the thermistor. My bet is the thermistor is dirty or it wasn't connected. Good luck!