Heater not working properly

If you have a temperature gauge that is stock, they are not very accurate. Especially if your thermostat is not quite closing enough to keep the coolant warm enough for interior or cabin heat.
So, you might try changing the thermostat.
Also, sometimes air gets stuck in the heater core. To bleed the air out of the system, try this:
Remove the radiator cap with engine cool
Turn heater all the way to hottest setting
Start car and bring to operating temperature
Top off and take for a test drive
You may have to repeat again after engine is cooled off.
See if that works.
A lot of engines have aluminum heads these days and barely stay hot enough to keep the heater core hot enough for warm cabin air. It is likely that the thermostat may be bad even if they are no other issues. You might also try replacing the radiator cap as the system will not function correctly if the cap has gone bad.

Hi,

As long as you have antifreeze in the engine (50/50 mixture) you should be fine as far as the engine freezing.

However, I don't think that is what you needed. I believe you need directions for replacing the heater core. So, if that is the case, here is a link that explains in general how it's done. Take a look through the link and let me know if you are comfortable doing it. Also, let me know if there is anything I can do to help.

https://www.2carpros.com/articles/replace-heater-core

Let me know.

Take care,

Joe