Heater core with A/C

[DirtyLarry]

Agh!

I had to open the ball valve to the heater core a few weeks ago when in the mountains as we needed heat and I noticed a few drips of coolant on the garage floor since I’ve been back. Finally got around to putting a pressure tester on it tonight only to find coolant leaking from the bottom of the heater core box. Checked the carpet under the Husky floor mat and...yep, it is wet too.

I have never had to change a heater core in this body style truck. How bad of a mofo is this job going to be with A/C?

[hrc200x]

I used to think that all 5 or 6 of the bolts on the firewall had to be removed to do the job, which meant pulling the inner fender to get to the one below the blower motor, but that isn't the case. You'll see 3 studs with nuts on the outside of the firewall, remove the nuts and then you should be able to pull the whole plastic thing inside the cab out. That of course is after you take off heater hoses, unhook any duct work. Not sure if vaccume lines under the dash need to be removed or not.

[KShortell]

It's not too bad and like hrc200x described. I did pull the inner fender when I did mine several years ago and I found it made it easier for me. It's the lowermost bolt and nut that's the tricky one.

The great news is that the inside, underdash stuff is pretty straightforward. Just don't force anything and you'll be fine.

[PackerBacker]

Originally Posted by hrc200x

I used to think that all 5 or 6 of the bolts on the firewall had to be removed to do the job, which meant pulling the inner fender to get to the one below the blower motor, but that isn't the case. You'll see 3 studs with nuts on the outside of the firewall, remove the nuts and then you should be able to pull the whole plastic thing inside the cab out. That of course is after you take off heater hoses, unhook any duct work. Not sure if vaccume lines under the dash need to be removed or not.

This was the single most helpful post I found on the subject, after searching extensively. Couple of things to add: the studs will likely break when you try to take the nuts off. Mine did. Easily replaced with new hardware. Also, there is one bolt on the inside that needs to come out. It's on the far right hand side of the plastic box assembly, inside the cab.

[tucsonjwt]

Scroll down on this thread and you will see some good pics on where the bolts are on the duct work, and info on replacing the heater core.

http://67-72chevytrucks.com/vboard/s...ight=defroster

I don't see any need to remove the inner fender. I did mine without removing it and I have A/C.

I recommend a good inspection mirror, flashlight, and flexible shaft for your ratchet so you can get to the bottom nuts on the firewall. Harbor Freight has a good set of flexible shafts for a few dollars.

I also recommend a copper, not aluminum, heater core.

[Rogue_Alphonse]

I ripped out my inner well, but it was in need of replacement anyway so I just killed two birds with one stone. I had an issue getting the core out of the box once it was removed though, so I kinda had to force it out.

DEFINATELY go with anything but aluminum. Really, when I did mine, I should have just brazed the inlet pipe back onto the old brass core. That was why it leaked.

Double whammy for me using the aluminum core is the fact that I have a diesel. You get heat in about 15 YEARS...