1972 Corvette, 350, A/C, 4 speed
How difficult is it to change out the heater core?
Where is the best place to buy Corvette replacement parts?
What is the best site for online manuals?
Thank you

 

Hi RB,
Welcome!
First post!!!

Changing the heater core on a 72 with a/c is a lot of work.
There have been some threads here about the work involved, so you might want to do a 'search' to locate them.

There are several good Corvette parts suppliers:
Corvette Central
ZIP Corvette Products
Paragon Corvette Reproductions
Wilcox Corvette
Most suppliers stock the same parts because there are actually relatively few parts manufacturers.

Most people like to have:
The 'GM Assembly Instruction Manual' for the year car they're working on.
The 'GM Chassis Service Manual' for the year car they're working on.
I much prefer the printed copies of these.

Good Luck!
Regards,
Alan

These are the manual for 71. You'll want to order the manuals for 72.
They're available from the suppliers I listed.

 

Replacing the heater core in an AC car, is a major job.

GM use to issue what they called the "Flat Rate Book" to dealers, that gave them the allowed time and labor to do repairs on new GM cars. The old GM Flat Rate books, use to give Chevrolet dealer mechanics about 8 hours, to replace the heater core on 68-82 Corvettes with air conditioning.

Original AC Delco cores are no longer available, and I don't know of anyone making heater cores in the US anymore. The best replacement ones currently available, seem to be coming from Mexico.

If you're going to do the job yourself, in addition to the books listed by Alan, make sure to get a complete AC heater box seal kit, and a set of correct AC heater hoses with molded ends. Standard hoses, without the molded ends, will kink where they enter the core, restricting coolant flow.

The AC heater core is replaced from inside the car, though you may find that you have to remove the outer box too, to access one mounting stud. The tubes on your new heater core, may not line up perfectly, this is nothing new, even the Delco ones were often misaligned. By gently bending the them, you can re-position the tubes. When doing the job, I remove the top, and passenger side seat, to give me a little extra work space.

 

Time consuming but no special tools or knowledge required.
Before you dig into the dash think of anything that's not working and be prepared to replace them "while you're at it".

The 72 350 wA/C heater core comes out from inside the car.
From the engine compartment drain the coolant, remove both heater hoses (razor knife is your friend). Do this first as you'll need to raise the car to get to the heater core hoses - the clamps can be difficult.

Remove the right hand dash pad and center gauge cluster (this is the majority of the work).
Remove the duct work covering the heater core - defrost duct + center assembly. On the engine/firewall side you'll find a single nut holding the only stud on the assembly in place. Locate and remove that nut (It's on the right side of the heater core as you look at it from the engine side - think at the top - straight back behind the pass valve cover) and the duct assembly covering the heater core should come right out. Remove the retaining straps and the core should lift up and out.

You can pressure test your new core with compressed air and an old bike tube.
Cut the tube at the furthest point from the valve stem and attach the two open ends of the tube to each side of the core using a hose clamps.
Apply air pressure to the valve stem (don't over do it) Bike pump works well for this.
Place then entire assembly in a sink of water and look for bubbles.

 

Take pictures as you remove parts, bag them with notes where they go lots of different size of fasteners. Take your time, and be gentle with the plastic as it becomes brittle over age. Buy band aids too. Do not have any children in your work area, as they will hear new phrases as you do this heater core. Easily a do it yourself job, just time consuming. I also removed the seats to get more room. Youtube has some good videos on the heater core too.

 

Pretty sure the heater core was the first part of the assembly line and they built the car around it. Major PIA job but easily doable. Just be patient and expect to walk away from it a few times. Pictures and baggies as said above is a good idea.

 

I did my ac car last year. Not hard just a PITA! If leaking at all plan on replacing the carpet and jute

 

I did my 72 eight years ago. Bought mine from NAPA, made in Mexico. Fit was good. This is not a highly technical job. Takes time, with lots of small parts. There are several how to articles on this site and the web. Pictures look daunting, just take it one step at a time. The guys have given perfect advice. Bag, tag, document. Fix everything that needs repair while you're in there. It's a good winter project. Just have it road ready by The end of March.

 

a real PIA but doable , just be sure to compare the old with the new and make sure the tubes for the heater hose are very close in shape and orientation.

Did my 71 when the car was apart- returned a core as it was really off. the second one was close - just adjusted it with dowel sticks - stuck in the tubes.

Later on had the original tested and cleaned - found out it was good. (I had no leak it was a just in case as the car was apart. And the car was a disaster)

I agree it's a good time to change the box seals.

 

As hot as my interior runs I don't need a heater core and my car is a daily driver. Drove to work this afternoon in 40 degree weather and it was nice in my car. No chill and no drafts. It does help to have the hard top on.
My heater core ruined a brand new passenger side carpet by leaking. I bypassed it and have never had the desire to hook it back up. The only reason I'd do it to get some defrost action but a scraper works just fine. I can defog with just my blower motor.
BTW I have a non A/C car so mine will not be nearly as hard as your is going to be.