why isn't the blower working for my a/c and heater in my 2000 mercury grand marquis Ls

probably a bad blower motor. I would check fuses first. if good check to see if you have power to the motor. If you have good power and ground at the motor, put one in it.

how do I check too see if I have power too the blower motor

remove the connector, hook up a test light to a good ground. make sure the controls are set to "on". probe both wires, one should light the test light the other is ground.

come on guys ,stop and think! step 1 apply a ground and a 12 volt source to the blower motor if it dont work replace the motor , step 2 if it does work replace the blower motor resister . ta da

Ta da. Your an idiot what happens when you dont have power going to it? If it only blows on high then you know its a resistor. If you have power and ground to the connector then its the motor. Ta da!

read my answer again , as for u takin shit //what happens when you dont have power going to IT ,what is IT ,the blower or the resister . one of two thing the motor is pulling excesive amps in witch case the resister is most likley damaged or the resister is bad most all fail in the high position sorry if i offended you OKAY BRO

the blower does work when I put power to it

I have no power to my blower motor what can be the causes