The heating system is not working. It is a aroad hazzar as the windshield is not fully defrosted.
You are the hazard for choosing to drive this vehicle rather than having the HVAC system serviced and repaired.
Good advice above to avoid driving vehicle if windshield not ice-cleared. As far as what to do, if I had that problem I’d make sure the engine coolant was at the proper warm-engine temperature. If so I’d feel the two hoses going behind the firewall to the heater matrix withheater on full blast and engine warm. If one of the hoses is hot, and the other cold, something is preventing the hot coolant from flowing through the heater core coolant circuit. If both hose are hot, coolant is flowing through heater core ok, and problem is the hot air is not being blown into the passenger compartment. Most likely that would be a faulty heater blower motor, hvac door routing, etc. Suggest to ask your shop do an investigation.