Heater blower on 2000 Kia Sephia

barely blows out air- what could be a quick fix or things to check???
PASSENGER door will not open- nothing appears to be broken???

Asked by for the 2000 Kia Sephia
check your coolant level and then make sure your thermostat is working. Do yo have a Check Engine Light. I ask this because I have replaced a few thermostats in KIAs for thermostat 'incorrect warm up' codes for Emissions failures in Calif. I do this type of work in CA.