Getting hot full of coolant

start engine until get hot enough for coolant get hot pressurize then turn off engine check for leaking coolant hose.

SOMEHOW I BELIEVE YOUR TWO INTAKE & RETURN HEATER HOSES THAT FEED THE HEATER CORE HAVE BEEN REVERSED. EITHER THAT OR a plugged heater core

Check the hose going to the expansion tank, That it is not pluged up.

Stuck thermostat maybe?????

ADD COOLANT IN THE COOLANT OVERFLOW JUG UNTIL COOLANT LEVEL STOP DROPPING AND COOLANT LEVEL STAY AT THE FULL COLD MARK.PLACE COOLANT OVERFLOW JUG CAP BACK ON JUG.CRANK VECHICLE UNTIL ENGINE START WARMING UP. STOP ENGINE WAIT FOR A WHILE UNTIL COOLANT COOL DOWN TO KEEP FROM GETTING SCALDED. USE A LARGE RAG OVER THE OVERFLOW JUG CAP OPEN OVERFLOW JUG CAP A LITTLE AT A TIME REMOVE OVERJUG CAP CHECK COOLANT LEVEL ADD MORE. COOLANT IN THE OVERFLOW JUG.THEN START VECHICLE AGAIN.LET ENGINE IDLE UNTIL TOP RADIATOR GET HOT.THEN THERMOSTAT WILL BE OPEN.WHILE ENGINE IDLING WATCH THE TEMPERATURE GAUGE IN VECHICLE IF TEMPERATURE GAUGE START CLIMBING IN THE HOT ZONE.TURN OFF VECHICLE LET IT SET A WHILE THEN USE LARGE RAG REMOVE OVERFLOW JUG CAP.ADD MORE COOLANT, PLACE CAP BACK ON START VECHICLE AGAIN KEEP DOING THIS PROCEDURE UNTIL TEMPERATURE STOP CLIMBING HOT ZONE.AND WHEN COOLANT LEVEL STOP DROPPING IN THE COOLANT OVERFLOW JUG.AIR IS OUT THE SYSTEM, BUT KEEP COOLANT LEVEL IN THE COOLANT OVERFLOW JUG AT THE FULL COLD MARK.DONT OVERFILL.DONT LET COOLANT OVERFLOW JUG RUN DRY IF SO AIR WILL ENTER COOLANT SYSTEM BECAUSE COOLANT LEVEL WILL BE LOW ENGINE WILL START OVERHEATING.

sound like you have faulty low coolant level sensor in the coolant expansion tank.make sure coolant expansion tank has coolant should be on full hot mark when engine hot been driven.cold engine coolant level in expansion tank should be on full cold mark.

Probability 1) The thermostat is probably stuck open, coolant is not getting hot enough from the engine to provide heat.

Starting from cold, allow the engine to run and warm up. While doing this, feel the upper radiator hose - you should be able to feel the coolant heating up to the point the hose is uncomfortably hot. If it gets that hot, then go to next step.

Probability 2) The heater core flow is restricted, not allowing full flow of coolant into passenger compartment.

There are 2 smaller heater hoses that run to the firewall. Are either of these hoses getting hot? Both sides hot indicate full coolant flow. Both sides cool indicate heater control valve not opening fully.

CHECK COOLANT LEVEL STILL LOW.ADD MORE COOLANT.UNTIL RADIATOR OVERFLOW FULL AT COLD MARK.THEN CRANK ENGINE UP LET IDLE FEW MINUTES LOOK DOWN COOLANT OVER FLOW JUG ADD MORE COOLANT IF LEVEL DROPPED.WHILE ENGINE RUNNING KEEP EYE ON TEMPERATURE GAUGE.WHEN THERMOSTAT HOSE GET HOT.TURN OFF ENGINE WAIT A LITTLE WHILE TO KEEP FROM GETTING SCALD TAKE LARGE RAG PLACE OVER OVERFLOW JUG RADIATOR CAP.OPEN CAP A LITTLE A TIME.IF COOLANT TRIES BOIL OUT.LET VECHICLE SET A WHILE LONGER.ADD MORE COOLANT.WHEN COOLANT LEVEL CORRECT AND ALL AIR OUT THE COOLANT SYSTEM.IT WILL STOP OVERHEATING.LONG AS ENGINE RUNNING HOT TURN OFF THE ENGINE POUR IN MORE COOLANT UNTIL COOLANT LEVEL STOP DROPPING IN RADIATOR.KEEP COOLANT LEVEL IN OVERFLOW AT COLD MARK.DONT OVER FILL OVERFLOW JUG.

How about the thermostat?

If your getting heat out the vents, the coolant is full, the upper hose is hot and the lower hose is cold that the t'stat is not opening.

If both the hoses are hot, the coolant is full, and you feel the fan pushing hot air than check the front of the radiator for debris build up. If there is no debris than the radiator could be plugged internally or the cooling fins may be severely rotted.

If the coolant is full, there is no heat out the vents and the upper hose is hot/lower hose is cold the water pump is not circulating enough coolant.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

does the blower still work?? Are you waiting long enough for the engine to warm up?? your heat comes from the engine heat. hot coolant (antifreeze) flows through the heater core (like a smaller radiator) behind the dashboard. the blower pulls air through the hot heater core, making the air hot.
If it blows air, but never gets warm, you should first check your coolant. if you drive your car without it, you will have big, expensive engine problems. If there is no coolant or very low coolant, you need to check for leaks after you refill it. (make sure you get the right kind of antifreeze. autozone can help)
most cars that new dont have radiator caps. Instead there is a seperate coolant tank under the hood. fill it to the full mark, let the car run and watch it. It will **** down the coolant from that tank untill the radiator is full.
If you have plenty of coolant, you may need a new thermostat. sometimes they get stuck. some stick open, some stick shut. It is usually easy to change one and they are cheap. I can't help you much with that cuz its different on every car. on my car, I have to crawl under it to get to the thermostat. hope this helps.