yes, i searched.

89 xj, 4.0, auto, red

when im cruising around town, 45-50mph, my a/c fan speed blows consistently. each speed blows properly. when i get on the freeway, the fan fluctuates. switch is on high but the blower will slow down for a minute, then speed up, etc. over and over till i exit freeway and slow down. it does the same thing in the winter with the heater on. it doesn't matter whether it's on recirculate, fresh or bi-level or what fan speed it's on.

is this the blower motor resistor?

thanks

 

check defrost vent when ac slows down sounds like vacuum issue

 

i will check that, thanks