Engine Replacing A Heater Core

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donald1956

New Member
Nov 6, 2011
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why cant a hole be cut in firewall to replace heater core in 1989 mustang just replace it with new piece of metal curious has anyone ever tried this will it work it would make a hard job simple the next time
 

FourEyed

Active Member
Jan 9, 2011
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why cant a hole be cut in firewall to replace heater core in 1989 mustang just replace it with new piece of metal curious has anyone ever tried this will it work it would make a hard job simple the next time

You maybe onto something..

I think it would be great to be able get to it through the Cowl Vent Grill somehow.:shrug: you know.. just reach in there and pull the sucker out.:D
 

1200gt

Active Member
Nov 29, 1999
358
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did anyone realize this thread is almost 4 years old?

That's the BEAUTY of Stangnet Forums, people still benefit from information no matter how old it is, as long as the car remain the same...:SN:

BTW, I had my other 86 a/c done by an Certified A/C Mech. and I watched them pull the whole dash in one piece, never disconnecting MOST of the wiring (1986 convt.) and using coat-hangers to hold the dash up on the top-latches while they pulled out the heater box assembly. This was one of those days that I was glad that I snooped around looking into the shop while the guys worked.:pop:

Now I have my other 86 vert to do myself - that-is, whenever I finally get some spare time! Working like a dog lately.

This was a great post and for good reason it is a "STICKY" Post.
 

1200gt

Active Member
Nov 29, 1999
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I changed the heater core in my 87GT years ago, i remember wishing i would have taken a pic of all the stuff i had to remove to get at it. I changed it while parked on the street in from of my house and boy was that a mistake!
After all was said and done I couldn't believe how inexpensive the core was and how ridiculously expensive labor is...but at least i knew why in the case of the hidden heater core.
Has anyone ever tried to make a simpler way to the "hack job" method? I mean incorporating a clean cut out and rivet system to aid in future exchanges?
Usually I only change the core once if at all with each fox i get but it would still be good to know if i had to do it again on the same car it would be a 20 minute process instead of 2-3 hours.
Like some previous people stated it can be done in 1.5 hours once you get familiar with it!

Thisis a GOOD question!

I was thinking the same thing. Would have been nice to have a panel to remove in the engine compartment where you could just slide it out from there; but then Ford would have missed out on all that Service Dept. Money:uzi: KILL-Hem! KILL-Hem!

Actually as engineered, the engine would be in the way, but dreams never die!
 

1200gt

Active Member
Nov 29, 1999
358
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39
Here's what my ALLDATA says:
198793heatercoreinstruc.jpg

198793heatercore.jpg


Hope that helps.

I wonder if all the YEAR FOX MUSTANG Heater Core Assembly's are the same???? ie. 79-93 Fox.
 

7991LXnSHO

wanna catch the space herp
10 Year Member
Sep 1, 2010
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Actually, the early ones without factory air were at least installed differently. I thought that was a question asked when I got the part - "AC or no AC/dealer air?" My 1979 with dealer air was a lot simpler operation. Remover 4 (or so) screws for the glove box, and there was a nice plate on the firewall, that once removed let the heater core fall into your lap. I was SHOCKED first time I read what it might take on my 91! This is some of the worst engineering I have seen.
 

mikestang63

SN Certified Technician
Aug 27, 2012
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In the garage
You'd think by now somebody would have come out with a replacement firewall piece that you could either weld or screw in. It would make this PITA job like an hour instead of 6 hours. I've see guys hack and cut out the HVAC box and then silicone or putty it back together.
 

HDTony

Member
Oct 15, 2010
134
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Plainfield IL
I have 3 screws out of this damn lid at this point. can not get to the passenger front screw. I think I may be cutting the cowl tomorrow and building a sheet metal piece. Ive got 4 evenings into this this already
 

Spaz

Member
Jan 5, 2013
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Pennsylvania
I was really just trying to replace the evaporator for an all-new Classic Auto Air a/c system. My plan was to replace the heater core while I had it apart. After trying to figure out how to get the evaporator out for about a half -hour, I figured I'd check online. It seems you can't remove the evaporator without removing the ENTIRE HVAC box assembly. So that new evaporator will be sitting in my house for years.