Why no heat

It could be any of the following items:
Coolant Level...cheap diy fill up
Thermostat stuck open...cheap diy replace
Heater Control Valve...not likely
Temperature blend door...check under dash for gear movement
Plugged heater core...easy diy
Blower motor resister...cheap diy replace

Cheapest, free place to start is remove the hoses to heater core on the firewall, use garden hose to flush both in and out tubes..muck and rust will come out..gently increase water pressure at the tap, so get a helper..replace hoses and tighten, test for heat, if yes, replace coolant with fresh coolant..if still a problem, replace blower resister located in or near glove box, if still a problem, replace thermostat..

If all these fails to rectify the issue, replace the water pump..not easy but doable..and more expensive.. cheers and good luck..

flushing a cooling system is the same method as any other motor

do it without the thermostat fitted
or water pump opening

sacrifice an old radiator hose to adapt a garden hose fitting
for radiator flush

air in system fix
your thermostat housing has no air bleed valve
no top radiator cap

old school way
heater on full
run motor till thermostats fully open
burp radiator hoses
wait till water is running up into over flow bottle without bubble
replace cap
turn off heater
correct level in over flow bottle

why still over heating
you fitted everything i would have ... yet still overheat
possibles
leaking inlet manifold gaskets
hose clamps loose
cooling fans spinning too slow
thermostatic fan switch faulty
aluminum radiator is a big one
air ..fins bent or some water channels blocked

or possible head gasket leak

IF YOU CAN'T FEEL THE AIR FLOW OUT BUT YOU HEAR THE BLOWER MOTOR WORKING, BEHIND THE GLOVE BOX IS A CABIN FILTER.REPLACE FILTER
IF YOU HAVE GOOD AIR FLOW BUT NO HEAT:
1;VACUUM LEAKING TO HEATER CONTROL
2;WATER PUMP GOING BAD / NOT CIRCULATING COOLANT,HIGH RPM/MORE COOLANT TO THE HEATER CORE
3;OPEN THERMOSTAT/ENGINE TEMPERATURE TO LOW
1;CHANGE THE DIRECTION FROM VENTS TO FLOUR TO WINDSHIELD. IF NOTHING HAPPEN IS THE VACUUM
2;RUN THE ENGINE INSIDE ON WARM PLACE ON IDLE.NOTE THE GAUGE IF PAS 1/2 TO 3/4. IF PAS 3/4 MARK REPLACE WATER PUMP
3;IF GAUGE STAY BELOW 1/2 REPLACE THERMOSTAT
GOOD LUCK

This is most likely the blend door. It controls the hot and cold air. Check to see if you can view the plenum behind the glove box to see if the levers are working that move this door.

If you have no heat in your vehicle then it is probably the heater core which is just a small radiator that sits behind the glove box. The thermostat itself is probably located where your top radiator hose connects to your engine. It is an easy and cheap fix, just pull the hose away after undoing the clamp and you should see it. If it is not there, then it will be in the bottom hose. Hope that helps you out.

sounds like the air blend door actuator motor is stuck on cold position.

If it is fogging your windows, you have a leaking heater core. Dash removal is required to fix it.

See if there isn't something here that might help:

https://www.cargurus.com/Cars/Discussion-t2530_ds537275

The heater not working.This problem is related to few possibilities 1) The thermostat can be faulty. 2) the heater blower motor resistor is faulty 3) The heater blower motor it self is faulty. ------------ The The blower resistor is behind glove-box on plenum.Connect the 12 volt battery directly to the heater blower motor and see,if the motor runs then its faulty resistor or thermostat.but if no motor running then its faulty motor. The thermostat is located at the top front of the engine.For easy access follow the top radiator hose.The top radiator hose goes in engine .Take that hose out and thermostat will be seen inside. --------- The thermostat and resistor are not very costly part.So you can directly replace them and see if its helping.First confirm motor is working,by directly by passing the blower motor to 12 volt battery. ------------ This will help.Thanks.Helpmech.

thats the resistor i think you can see glowing ,but the heat problem is a blocked heater rad ,try flushing with a garden hose ,