If you haven't seen it already, this may help. http://www.offroaders.com/info/tech-corner/project-cj7/project-cj7-heater.htm
The dash has to be removed to gain access to the heater box. The heater box then comes out and is split open to replace the core.
Remove the water supply hoses from your 1985 Chevy heater core. Remove the heater core retaining bolts. The heater core will come out. Reverse the process to install your new heater core.
To replace the heater core of a 1985 Bronco 2, open the glove box and push on the 2 tabs that hold it in place. After removing the entire glove box, remove the round plastic screws of the heater core. Remove the old and replace with a new one.
If they disconnected the heater core, it means it was leaking. Get a manual on your car from the parts store and it will show you how to replace the heater core also
get a manual on your car from DISCOUNTAUTOREPAIRMANUALS.COM and it will help on the next repair also. This is not an easy job.
remove 2 bolts holding it on,then replace, follow line back to bleeder valve,bleed,then bleed at slave cylinder
You have to remove the steering wheel, and it requires special tools.
You need to replace the rubber seals in the master cylinder. May even have to have the master cylinder re-sleaved.
you have to remove the dashboard top. It is located in the right hand side of the dash. It is a little work but you can get it out.
Remove the water supply lines to your 1985 Pontiac Trans Am heater core. Remove the heater core retaining bolts. The heater core will come out. Reverse the process to install your new heater core.
You can find the 1985 VW heater core behind the drivers side kick plate. You will need to remove the kick plate in order to access the heater core.
The heater core on a 1985 Chevy Suburban is located under the dashboard on the passenger side of the vehicle. The glove compartment may have to be removed to access the heater core.