I have a friend with a similar situation and his seemed to work only at certain temps and then stop quite quickly. He had the main system totally redone and the final price was lol 800.00. Still no result after redoing the entire underhood system that was leaking.
Soooooooo I will be helping my friend (for beer not money..lol ) with his under dash portion of the system and would love to find out how it turns out for ya. I will let you know how it goes on our end but I believe his is a sensor or some other component. I am going to replace major parts all the way down the system until I find the problem. Weeee

Ty

i think its just the evap core needs to be cleaned too now, but I dont know where it is?
would anyone here be willing to walk me step-by-step through this, i dont know where to start at...

Start at the TechInfo link at the top of this page, click on the Tech Know-How link, and look at Item 35 on the list...

I read the first step, but where is that at?

You mean this?

It'* referring to the big black plastic cover on the firewall, passenger'* side, reading "MAXIFUSE RELAY CENTER" across the front. Unscrew a couple of stamped wing nuts on the top and it should come right off. (You _are_ under the hood, right? It'* on the engine side of the firewall, not under the dash.)

Your auto shop isnt full of ****, he is just confused. What he is most likely thinking of is the older, origional GM Electronic Climate Controls from the early 80'*. There was a electronic circut board that was mounted in the air stream for the HVAC system under the hood. If this module went bad it would default to HI fan speed and DEF mode. If this board went bad it was HELLA expensive to get it replaced. My dad had a 81 Cadillac that it went bad on, he got it at the junk yard for $100, Dealer wanted $500. It went on his 83 Riv too, and on our old 82 Buick Electra wagon. So, he just was trying to help out. Old people get confused.

Jay

yeah thats what I meant, now uI understand,but then.... what is the relay rail?

That would be the assembly holding the bank of relays that you'll uncover when you remove the big black plastic MAXIFUSE shield.

I would suggest taking the printout of the procedure out with you to the car and reading through the steps as you go. I think you should figure it out as you work through it. If not, maybe there'* a mechanic you could show that procedure to who could identify the relevant parts for you...?