New here. Didn't see a designated spot for Full size blazers. I have a 89 Full size looking for guidence on replacing the heater core and I also have a hard shift between 1st and 2nd. I already bought the heater core and looking at putting it in this week. My transmission is a 700r4. It shifts hard between 1st and 2nd when driving regular speeds, but when I get on the gas from a stop it shifts fine and smooth. I am lost on attempting to fix it or adjust it. Please help. Thanks guys.

 

Try checking the TV cable adjustment.

http://www.tvmadeez.com/article/index.php

!!CAUTION!!
Driving with the cable out of adjustment will ruin a transmission very quickly. So make sure you understand what you are doing before you try it.

 

Thanks for the link. I would rather have a good mechanic that knows what he's doing adjust it. Unfortunatly I live in Alaska where there is a shortage of great mechanics. I have taken it to 3 shops and no one knows how the hell to adjust it. I have even asked about the cable and they all look at it and say yeah it looks good. Without even touching it. I don't want to ruin anything,but I can't keep driving it like this. What is worst case if I don't adjust it correctly?i am considering going by the Chevrolet dealer.

 

if the blazer has been doing the trans issue for as long as you owned it its possible the previous owner had a shift kit put in it. my th400 will spin the tires when it shifts.

im guessing you have a/c. so much easier if you dont. its been a while since i did one but i think you have to disconnect the line going to the box at the fire wall for the a/c then there are bolts under the dash along with under the hood that hold thatbox to the fire wall. might even have to drop the wheel well to get at one. also dont forget to disconnect the cables going to the top of the box under the dash. maybe someone else will help better like i said its been a while. if its non a/c you can have that thing out in like 25 minutes

 

Thanks for the help guys. I dropped the trans pan...didn't find any chunks of metal or anything crazy. It was pretty clean. Cleaned the vaulve body. Still shifts hard. I think I will attempt to tighten up the TV cable this week. It does seem to have too much play in it.
The heater core replacement took me about 3 hours. It wasn't as bad as I thought. I do have A/C but I didn't have to touch the box. 2 bolts on the inside...fairly easy to get to(under glove box). 2 nuts on the firewall side below A/C box. I used a long socket 7/16 on an elbow and a very long extention(3 foot). Was tons easier than taken that inner fender off. I did take out my passenger seat, glovebox and ashtray. Not too bad of a job and smells way better with no leaky mess on the carpet! Thanks again.
If anyone else has anymore input on the trans please share. Not sure if I should just rebuild or wait till this one blows up.