Topher5150

98 F150
I notice on these cold frosty mornings i'm just blowing cold air until I take off from a red light in a spirited manner then I hear something under the dash move then the defrost kicks in. Could it be, and I'm praying, that the actuator motor is that dead that it needs to be jolted into place. I haven't taken anything apart yet so I haven't been able to test the motor.

djfllmn

iTrader: (1)

that era F150 did not use electric motors for the blend doors, all vacuum operated. you are loosing vacuum somewhere because when you get on the gas vacuum drops and then it defaults to defrost

Topher5150

Is this located near the floor?

djfllmn

iTrader: (1)

whats near the floor?

Topher5150

the actuator

djfllmn

iTrader: (1)

no, that one is not.

djfllmn

iTrader: (1)

i stand corrected, there is 1 electric motor in that system, it is indeed the blend door motor and it is on the bottom of the box. But your problem does not sound like a bad blend door motor