Help on Heater Core replace

[1970 CST Short Wide]

My heater core finally gave up the other day - antifreeze all over the floor
Any way, do I pull it from the AC unit or under the dash??? I'm thinking glove box out and under the dash; I'd hate to take the AC unit off the firewall

Any help would be appreciated, Oh ya it’s a 1970 with AC

Thanks
Steve

[LockDoc]

-
I don't know a lot about the air units but I'm betting it's on the outside.... Hoping someone will say I'm wrong for your sake. To get the outside air box off you have to take the inner panel loose, and I think the hood hinge off to get to a couple of the screws/bolts and get the box out.

LockDoc

[caminokid]

I am almost sure you have to pull the box off the outside. I seen and air box at the junkyard off. The core was mounted to the outside box.

[mrein3]

The AC heater core is inside. You need to get the box behind the glove box out. The heater hoses are disconnected from under the hood. There are studs sticking out of the heaterbox that need to be taken off from under the hood.

[Rdub]

+1 on MREIN's reply (comes out from inside) but, there ae some studs with nuts that come loose from under hood.... if you do a search there's a pretty detailed account of removing a heater core from an AC truck.

[kwmech]

With AC under the dash---without, under the hood with the hinge removal

[1970 CST Short Wide]

Thank You all. Now who wants to do it - LOL its like 107 outside today, NOT ME

[sameyrasmea72]

It is going to be so much fun!! A couple of the lower nuts on the studs on the outside of the firewall are nearly imposible to get to with the inner fender in palce. Good luck!

[70LonghornCST]

Originally Posted by 1970 CST Short Wide

Thank You all. Now who wants to do it - LOL its like 107 outside today, NOT ME

107? Not a problem, just turn on the A/C

[Rdub]

On removing those lower nuts from out side the firewall, choices are.... 1)completely remove the inner fender or, 2)drill a couple of large holes in the inner fender or, 3) what a lot of people do is just remove the lower bolts, and as many others as needed, that hold the inner fender in place, then you should be able to reach in there from underneath, through the tire well area and take the nuts off.

[PanelDeland]

Just loop the heater hose back to the other connection on the block,then wait for cooler weather.I don't think you're going to need it right away.

[1970 CST Short Wide]

More good info and your right I'm in no hurry to fix it. I already looped it

[Classic Heartbeat]

Make sure that you purchase a made in the USA heater core. Those seem to fit the best. I have seen many here complain about the fit on the made in Mexico one that you get at most parts houses. I recently sold a made in the USA A/C heater core to a customer in Seattle that tried to install a made in Mexico core that wouldn't fit. He reported back to me to tell me that the USA one fit great. WES

[jewels.]

If you are going to replace your heater core - here is a very old thread that I posted pics on my heater core replacement (nearly 5 years ago). It just might be helpful!

Oh - and do it while it is warm - you will thank yourself!
Have fun!
~jewels

[70LonghornCST]

Originally Posted by Classic Heartbeat

Make sure that you purchase a made in the USA heater core. Those seem to fit the best. I have seen many here complain about the fit on the made in Mexico one that you get at most parts houses. I recently sold a made in the USA A/C heater core to a customer in Seattle that tried to install a made in Mexico core that wouldn't fit. He reported back to me to tell me that the USA one fit great. WES

Exactly! Those non-USA ones' inlet and oiutlet tubes do not line up vertically. And if you try to force them you'll risk breaking the soder. I know, I've done it.

[scottbaxley]

Heater core replacement is pretty straight forward. The heater core comes out from under the dash with factory air as follows:

Drain coolant. Remove heater hoses. Remove inner fender from rt. side. Remove 5 nuts from the fire wall mounting the A/C box(the A/C will not need to be disturbed in any way). At this point, inspect all hoses, control valves, etc. Now is the time to replace these items!!

Now for under the dash: Remove glove box door. Remove glove box. Unplug A/C relay on side of heater box. Remove all ducts that are immediately on top of the heater box-usually resulting in ducts being destroyed in this year of vehicle due to age. Remove two 5/16" screws attaching mixing door assy. to heater box. Remove 3 5/16" screws attaching mixing door assy. to floor ducting. Slide the mixer door assy. forward and out of the way. Reach inside the heater box and unplug the fan relay, and remove wires from the box. Take the two 7/16" screws out of the box mounting it to the firewall. Remove the box containing the heater core.

After removing the box, you can see that the core is held in place by two retaining brackets-one on the front, one on the back. These are held in with two 1/4" screws each. Remove brackets. Remove heater hose tube hold-down.

Have a beer, you are half-way through!! Install new core into box. Install box back onto the firewall with two 7?16" screws ONLY. Reconnect all hoses. Fill with coolant. Start engine and bring to operating temp. Turn off engine and let the engine sit with pressure in the coolant system for 2o minutes. Check for leaks in the core, hose connections, etc. If there are none, reassemble.

This job takes approximately 3 hours start to finish, not including the beer!

[Stocker]

Hey Scott, welcome to the board from NorCal!

If an old thread's gonna be revived, that's the way to do it -- with a great first post, very detailed & informative!!

[RenoKeene]

Also welcome from Central Florida....ditto on a great post (kept me from having to type all that up )