1998 Mazda 626 replacement of heater coil

My sons 626 had anti-freeze pour out of the floor hearter duct on the passenger side. We've pulled the dash facing, but are at a loss to see out we remove the heater coil to replace it.
I've looped the cooling sys. Hoses so he can still use the car until we can repair it. Any help you can give would be great. Stuck in Houston.
Thanks.