replace a heater core on a 2003 honda civic ex

Hey, hey...

'Cutting to the chase', although the heater core is just a mini radiator hidden in your dash, it isn't easy to replace on your Honda Civic (or most cars, for that matter).

It is not a beginner do it yourself project.

You're going to have to remove the dash board and all its components, replace the core and connections, then reinstall everything...

Obviously, some of the other connections ( rubber tubing/hoses, clamps...) are located in the engine compartment and will need to be addressed, but those aren't usually very complicated.

Again, but that darn dash...and sometimes the steering wheel/column.

Oh, disconnect the battery - you don't want to be surprised with an airbag explosion from your steering wheel.

This is one repair that I always recommend to a service tech.

I realize that you're trying to save some hard earned cash, but this will be a challenge.

Best wishes.