heres my problem... my truck will start to shift hard once in a blue moon and i could never figure out why. finally today i was headed to work and was talking on the phone so i rolled up my windows and turned the A/C on max... shortly after i noticed that it was revving higher before it shifted but i didnt think anything of it... the i get on the highway and when i get of it slams into gear... i was like WTF!!! so i rolled down my windows and shut the A/C off... it started shifting better and by the time i got to work it wasnt shifting funny at all... now my question... why the hell would my tranny shift bad only after mt a/c is on?

it is a 94 xlt 351w automatic just to let you know... thanks guys

 

well when the ac comes on it increases rpm because of the extra drag created by the ac compressor. now your tranny is electric so the computer is telling the tranny to shift harder do to the added load thats now on the motor. when ac is off it doesnt need to act in that way. I suggest you get the tranny fluid and filter changed and see if that helps any. do you know when that tranny had been serviced last?

 

i had it flush just over a year ago... and since then i have not put that many miles on it

 

a tranny should get serviced every 6months to a year always depending on use. 1yr if it hasnt been driven to much. also have it scaned for codes.