1999 F150, V6, 5speed, extended cab.

System of course has a 4 speed fan Low, 2nd position, 3rd position, High. I can tell a difference between all 4 speeds, but it just doesn't put out much flow, or so it seems.

All these observered on A/C and Max A/C, so I think that is vent output only correct?

Even on High, it flows the most, but it just doesn't seem to be what it once was.

Could this be a blower motor problem? Or, is something limiting current to the blower motor?

I always thought that a blower motor is out when it doesn't turn at any speed setting.

 

have you had to charge your A/C resently sounds like evap. core is restricted. sometimes they leak out refrigerant. and leak oil on to the fins which in turn will collect dirt and dust.

 

Thanks. How does one get to the evaporator core for inspection / cleaning? I hope the whole dashboard doesn't have to come out.

 

on that model im not to sure the first thing i would do is remove the blower motor and look inside the caseing you may need a mirror you know one of those small mirrors that pull out and you should be able to get a look at part of it if you can see try gently useing compressed air see if you can get your hand in there it is possible however that you can not get to the evap core from there good luck but it sounds like a restricion to me.

 

There is a resistor bank associated with the blower motor. Your fan speed switch selects different resistance branches to apply the current to the motor to make it spin at different speeds.

Since the speed change is across the board I can think of 2 things. Either you have a bad resistor (or more) in the main branch which will affect all speeds or you may have a suction problem. My father was experiencing the same problem in his GMC and changed out the HEPA filters for the ventilation. Solved his problem instantly. If you have a ventilation filtration system I would recommend checking them for clogging/age. If you don't or those are fine the blower motor resistor bank would be my best guess. I haven't changed one on a Ford so I don't know if it's integrated into the blower construction (it was on my Mazda).

Good luck and I hope this helps.