My heater is suddenly not blowing hot air. on 1993 Subaru Loyale

Just replaced the radiator and the heater is now not working; it just blows cold air. I fixed my overheating problem now I have not heat....! Is this heater core problem or maybe something went wrong when I replaced the radiator??

Asked by for the 1993 Subaru Loyale
Perhaps air is trapped in the heater core after the radiator replacement open the heater valve fully hot position the two hoses going into the inside of the car at the firewall should be hot if fluid is going through the heater core.
Thanks! Will try messing with that tomorrow! I hate to have to buy a new core because they are so dang expensive!