Having problems with civic, just got new thermostat and new radiator put in car, still having problems with the heat, when the heat is on it turns into cold air all of a sudden and car got new radiator installed and now car overheated while driving, any advice on what could be wrong with it?

 

It's most likely trapped air in your cooling system. You may also need to back-flush your heater core.

 

also make sure your radiator cap is good. Pressure test it or replace it. Had 98 civic with a bad one and it caused it to overheat.

 

When the car is cold. Run it with the cap off and wait for the thermostat to open.

 

I believe this guy hit it right one!