How do I get my heater to blow thru vents?

Are you saying it won't blow defrost or it won't blow on the floor? are you saying it won't blow front dash vents? I'd have to check directional doors, under the dash. If an actuator door is vacuum controlled, I'd have to check that. Just my opinion.

If it will only blow through the defrost vent, the system has lost vacuum. Look for a disconnected vacuum hose at the firewall. Hope that helps! Jim