Chevy & GMC Vans

Hey y’all,
My heat recently stopped working in my van.
(1995 g2500)
The heat stopped and then it’s like the vent to outside is stuck open and I’m constantly getting blow even with the fan turned off.
Should I replace the heat core?
Any ideas on how to fix the issue would be rad.
It’s getting real cold out here in the mornings hahahaha.
But seriously, would be nice to have a warm van to sit in.

feel your heater hoses to see if they get hot (both). You could try backflushing it.
unless your engine is overheating I wouldn't touch the radiator.
I've never had a 95. Are the vents vacuum controlled? if so it's usually rotten vacuum lines. check charm.li for details.

Where would I find the heater hoses to check them?
Yes the vents are vacuum controlled.

typically coming through the firewall on the passenger side and going to the water pump. Diagrams are on charm.li