If the coolant level is okay, I would suspect a restricted heater core. Try flushing the heater core.
Your heater will blow cold air only.
It doesn't really blow it out it just warms the cold air.
Poor circulation from a restricted/plugged heater core. Try flushing it.
you need to replace your heater core
it wont blow heat itll blow cold air
you are low on coolingliquid !
heater core possibly plugged and leaking
The front expansion valve is clogged.
No, not if it's on a heat setting. Most home thermostats have a "Fan" setting that will blow cold air if the attic is cold.
you may not have the heater water hoses plugged in
No! Thermostat.