When driving my temp goes up to about 275, no hot air comes out of the heat vents.. then it will got back down to around 200 degrees and i will get hot air out of the vents. I have a few ideas about what could cause this, but fig i ask for other peoples oppions

it is an 87 iroc carb

 

Air lock. Warm the car up from cold with the rad cap off. Make sure the front right side of the car is the highest (jack it up if you must) in order to burp the air out. Keep fillng until it won't take any more and replace the cap.

 

Answered in other post -

please please only post in one section, whichever is more appropriate for your issue - double posting confuses everyone and wastes our time (which is precious to us, yet we offer it here for free).

 

To the OP - if you ever jack up just one side of the car, please do both front and rear at same time. These unibody cars can crack at the roofline if you jack up just one corner. Unless you have SFC's installed that tie the front and rear together, never just jack one corner - your stressing areas of the unibody that already get stressed enough while driving.