What would cause a 97 Chevy Lumina to only blow cold air?
Things to check/eliminate: Possibly the thermostat is stuck in
the open position and won't allow the engine to build hot water.
You can possibly feel if there is flow thru the heater hose near
the firewall. If you have recently replaced a broken hose this
could be a possibility. Could be the heater control valve is
inoperative. If no hot water is getting past the valve it will blow
only cold air. Suspect this valve is either vacuum/electrically
controled. Hopefully a vacume hose end rotted or theres a hole.
Fairly easy to replace or if its long elongh cut the bad part off
and reinstall Hope this input helps, Terry