I'm having trouble getting the new heater core into the HVAC box. I cut the hose bibs off the old one to remove it.
Do I need to remove the HVAC box to install the new heater core? If so, how do I disconnect it? I can't see how it's connected to the firewall.
Thanks.

 

I think its bolted in from the engine side of the firewall.

Grab the 01 service manual, procedure will be in there. (available for download in the faq section here.)

 

Every time I see a heater core post I do a little cringe....Such a horrible job!!! Good luck

Also, you shouldn't have to remove the box, at least I didn't.

Did you buy an OEM core from the stealership?

 

I read the 01 Service Manual but I'm still not having any luck getting the box loose. I think I'm going to put it back together and take it somewhere. If I could just pull the box back I couple of inches, I could get the new core in.
The new core is a Murray, from O'Reilly's. It has swivel arms on it which look like a leak waiting to happen.

 

The PCM has to be unbolted in order to get to all of the nuts that secure the plenum box to the firewall.

 

There are three small screws that hold the PCM to the firewall. They don't seem big enough to hold the heater box in place. Is the PCM covering a larger bolt?
I only found two nuts in the cab connected to the heater box. Are those two and the PCM all that holds the heater box?

 

The other bolts holding it on are accessed from the engine bay firewall side. Can't remember exactly where, just that they are.