Heater won't work despite troubleshooting

Heater stopped working who knows when. Houston, Texas rarely gets cold. Finally did this year and welp no heater. I've changed thermostat, engine coolanto temp sensor, fan temp sensor next to it since I was there, checked heater control valve, fully functioning, opens and closes no errors, with help from pops I turn the AC fan to 1 put the temp knob to the right on the red heat side and heven saw the valve open and close so the wire is ok and the unit is good. I feel I've done good so far so where do I keep going I feel I did all the small cheap stuff first. What's next, I got no codes so that won't help.

first of all check your coolant level. isis full . is there any leaks ? have you had to top it up before recently?

second of all dose the car warm up to opperating temp? i see you changed the thermostat. dose the temperature gauge read in the middle after its been running for a few minutes?

what it sounds like is a heater core problem.

loook in the engine bay and you will see two hoses going into the fire wall. one withe heater controll valve which is the inlet to the heater core. 1 leaving the firewall which is the outlet.

when the engines running and at operating temp. set ur heat dials to hot go out and grab/grasp both hoses with your hand. one will feel warm the other should feel slighlty less warm due to the fact the heater core acts as a cooler. if one feels warm and the other feels cool. this indicates a clogged heater core.

problems could also be a bad blend door in the hvac system inside but most likley a faulty heater core im guesssing. good luck and keep me posted