i have a 88 f150 and the heater has a problem. it works great but there's only two setting on or off. the heater adjuster doesn't work in between full blast and off. any ideas i already tried putting in another heater switch part behind the ****.

 

Try the blower motor resistor. I think its located on the front side of the blower motor housing. Better look at a manual, been a while since I have worked on that year. The resistor controls the amount of juice to the blower motor after the setting at the selector is made.

 

If everything works except ALL the reduced speeds, then it MUST be the resistor. On all '80-96 with A/C, it's located at the green pointer in the 1st photo below.

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thanks i'll try the resistor and let you know if it works.

 

Yuppers! Resistor pack is shot. Luckily, it's one of the few cheap parts on it... $15 last time I checked.

-Joe