I have a 2004 Pontiac Bonneville with 95000 miles. The car takes a long time to produce heat out of the vents in the car. The blower fan works and the engine temp seems to raise normally.
It eventually gets warm, but it takes a lot longer than it used to.
Is this from clogged, or partially clogged heater core? Could it be the water pump going bad?
How often have you been changing your coolant?
I’ve never changed it.
Then a nearly clogged heater core and/or a failing water pump are both good possibilities.