May I respectfully suggest you actually get a coolant temperature.
Get the engine up to 'running" temp, if you have a heat gun, shoot the top rad hose temp. If you need to go borrow the wife's/neighbors meat probe, same think, stick it into coolant at rad cap.
The coolant temp needs to be +160* to get "warm" air outta the heater duct.
If the thermostat is stuck open, the heater hoses will feel warm, but not near hot enuff.
For decent winter heat, 180* is normal to get regular heat, the 195* thermostat is for really cold climate where the ambient air going into the heater is frigid/polar.
Just before you tear the dash apart, make sure the coolants hot enuff.
Go check the temps on your daily driver for comparison .
Good luck .
