Covah161

My son’s AC blower on his 2009 F150 doesn’t seem to be blowing hard. It is a manual system. We changed the blower motor, it seemed a little better, changed the resistor for speeds, made no difference. There seems like there is a big drop off from speed 4 to 3 and 2 and 1 not blowing much. Should there be a difference when you click on max ac? There is no difference. I know the evaporator coil may be clogging but trying to eliminate everything else first. Thanks in advance.

ProjectSHO89

Check to see if the evaporator is clogged (dust, dirt, etc). causing restricted airflow through the system.

Technically no but, since recirculate takes less work to move the air, a greater amount of airflow is possible and is usually observed as the blower motor has less of a load on it.

Covah161

What about the control head or blower switch? Thanks

ProjectSHO89

What about them? They aren't your problem.

lucasjcdr

if my fan speed is all the way up and recirculate is already on... then max wont change anything. Max is for when your fan is lower and recirculate is off, when you click max its designed to turn on recirculate and max out the fan speed.

Covah161

Thanks, why do you think the fan is not blowing hard on high? Clogged evaporator?

ProjectSHO89

Isn't that what I told you to check the first time?

SOMETHING appears to be restricting airflow. Clogged cabin air filter (perhaps added after manufacturing since they weren't standard on that era of F150, Debris, or a dirty evaporator are you likely choices. You have to open it up and inspect, the keyboard only goes so far....

lucasjcdr

the fan should get a little louder with each speed increase, if the speed is increased and you can hear the fan spin faster but the output doesnt change... then logic says that it is blocked somewhere.