Yes, if you break open the A/C, you MUST evacuate it, then recharge.

If you hold your face just right..... you might be able to change the heater core without completely removing the box..... If you are going to open up the a/c system anyway, replace the evap core as well.... you are RIGHT THERE..... and they are famous for failure in any event.

 

and i do not have the equipment to evacuate the system... so it looks like i will be trying to just pull the box out enough. do you have a suggestion for the type of core to buy, i bought one from autozone but i really dont like the flimsy tubes...

 

I personally prefer the all brass/copper guys. I haven't had to do my heater core yet..... so, not sure about sourcing/availability. Basically, check local parts stores, and see who has what.

 

You'll be sorry down the road if you do not replace the evap core also. After the repair bring it to an AC shop and let them evac and charge the system.