On My 2003 Mercury Grand Marquis my ac does not blow hot or cold air. It just blow cool air. It gets cold at night time though.
The Heater core could be clogged. Check to make sure that the coolant is full and flowing at operating temperature. You may need a cooling system flush (or back flush)
Blend door actuator stuck?
That's a possibility kbro. And a bummer to change out.
Dash has gotta come out for that one right?
I can control the speed of the blower but not the temperature!!!
Yup. That's a Blend Air Door Actuator. It sits on top of the heater case tucked under the dash. You can try accessing it through the glove box by pulling the glove box, passenger's air bag and right vent ducting BUT....you run the risk of damaging the heater case and tearing up your arms.
Looking for a Used Grand Marquis in your area?
CarGurus has 1,813 nationwide Grand Marquis listings starting at $1,600.
Search Mercury Grand Marquis Questions
Mercury Grand Marquis Experts