how do I replace the BlendAire actuator on my 2004 Grand Marquis... It only blows hot air. Is it possible to move door to cold side only and block it to have cooling & no heating???

The blend door is a function of the engine. It opens up when operating temperature is reached. It's only purpose in life is to let preheated air be used, from the stove kit on your exhaust manifold. Why this should be of concern to you, not certian. if your vehicle is taking to long to come up to operating temerature, the blend door need to be looked at. I'd concern myself with the stove kit and connecting pipe, more so than the blend door. if you've got bad heat, would look to the thermostat being stuck open first.

We are talking about Automatic Temp. Control inside vehicle. 2004 Marquis doe's not have heat stove on X manifold...

Okay then, we must ask why aren't the signals to open getting through. If you put a new one in, the same result~ if it's tubing that fell off or is cracked, inspect. If you've got a suction instrument, a turkey baster might work, to actuate manually, then inspect, you can see if this unit is bad, rather than the thing what gives it instruction.

http://diy-auto-repair.wonderhowto.com/how-to/fix-blend-door-actuator-motor-99-mercury-grand-marquis-396512/

I had the same problem years ago on my 1996 Marquis...couldn't afford the dealership price so I just turned off the A/C....until...I had to change out the battery. Changing the battery made the blend door actuator cancel a code and it began to pop once in a while and so I turned on the a/c...it worked! Now, if I hit a bump or (it has worked for a few years in a/c only) jolt the door in some way it will turn to heat only....I just get out and take the neg off the battery for a few moments and then attach it back...the a/c will then work again!

I would to know how you move the duct when replacing blend door actuator on 1998 mercury grand maquris