I'm getting cold in here...
 

i have a '97 LT1 T/A. 75,000 miles. water temp is at 175-180 in town and on highway. antifreeze is good and full. i turn the heater on and at first it shoots good hot air, then goes right to cool. not A/C cool, but just cool. do heater cores go out this quick in these things? or am i missing something. i hear the fans and ducts switch on and open, but nothing but cool air flows out. thanks for any help guys/girls.

may need to flush out the heater thing

If you can get to the hoses going to your heater core through the firewall, feel them. If the heater is on and only one hose is hot, you probably have a clogged heater core.