This happened to my 2005. The blend door actuator was the culprit. A real pain to change but doable. I'm not sure if your model is much different than mine but the dashboard had to be taking a loose and pulled back enough to get my hand in there and get the screws out to change. I believe I found youtube videos that helped me out.
2000 Mercury Grand Marquis LS
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Maintenance & Repair
I changed the heater contol butthat was not the problem. I bypassed the heater coil and the ac works fine. Is there a door that directs teh air over the heater coiol?
2001 Mercury Grand Marquis GS
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Maintenance & Repair
Just blows hot air usually out the heater ducts or defroster vents. has the dual zone climate control wish I didn't now! but no matter what I set it to. It blows hot
2004 Mercury Grand Marquis GS
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Maintenance & Repair
Heater blows warm air in the summer with controls set to off. Heater blows cold air in winter controls set to on. Thermostat replaced, new radiator, new blower switch, new heater control valve. Any...
1987 Mercury Grand Marquis LS Sedan RWD
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Maintenance & Repair
air conditioner and vent blows hot air, it corrected itself for a day or so then went back to hot air again
2000 Mercury Grand Marquis LS
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Maintenance & Repair
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