How To: R&R Heater Core in 71-74 Buick, Fullsize

This should serve as a guide to removing and replacing the heater core in a 1971-1974 Fullsize Buick including, Electra, LeSabre, Centurion, Riviera and Estate Wagon. There will be minor differences between the years, but the basics are the same. This write-up was done on a 1971 Buick Electra 225 Limited with air conditioning and automatic climate control.

1. Disconnect negative battery cable 8mm wrench (or 5/16)
2. Remove Fire Extinguisher (If applicable), remove contents of glovebox, remove floormat.
3. Use a #1 Philips Screwdriver to remove the (5 ) screws holding the liner to the dash assembly. There are three at the base of the liner and one on each side.

Shown below are four of the (5) screws removed.

 

4. Using a deep wall socket on a " drive ratchet, remove the (2) Hex head screws that hold the vent to the dash assembly.

 

5. Remove the (3) Hex head screws holding the glovebox door to the dash assembly. Keep the glovebox closed but not locked. It gives better access to the mounting hardware. Youll need to hold the glovebox door while removing the last screw. After the last screw is out, open the glovebox and carefully lower it to about normal height (I.E. above the seat bottom, level) and carefully turn it toward the passenger side of the car. Begin to pull it out towards the rear of the car but be careful as there is a rubber boot on the end of the glovebox arm.

 

6. Remove the gloveboxer liner carefully by pushing one side out of the dash opening and being careful not to tear the tabs on the liner. This takes some patience.
7. Using a drive ratchet with 5/16 deep wall socket, remove the (2) hex head screws holding the distribution duct onto the firewall half of the HVAC system.

 

8. Disconnect the upper blower duct (located on upper passenger side) and lower blower duct (located on lower driver side) from the distribution duct.
9. Carefully pry the plastic hold-down above the “dowel” pins that locate it.
10. Remove the distribution duct, this would be a great time to spend a few minutes and thoroughly clean it surfaces.

The first picture is of the upper blower duct. Second picture is the lower blower duct. Third picture is of the "dowel" pins on the distribution duct. Fourth is of the distribution duct removed and cleaned.

 

11. Move the large drivers side HVAC duct (hose) toward the drivers side, preferably by the pedals. NOTE: If you have gauges and are running copper lines be careful when repositioning it to not bend the lines.
12. Using the ratchet and 5/16 deep wall socket remove the center floor vent, there is (1) hex head screw.

 

13. Remove the three 5/16 hex head screws holding the Delco Radio Automatic Climate Control (This is referred to the Programmer in the service manual) to the HVAC box Heater and Defroster Assembly. It has eight vacuum lines running to it. NOTE: My car has Automatic Climate Control, yours may vary.

14. If your insulation has fallen, It is a good time to vacuum out the loose insulation. Dont remove any if its still intact.

One screw is on top, two are at the base of the programmer.

 

15. Using a 5/16 wrench loosen the hex head screw on the shaft that connects the DRACC or Programmer to the Temperature door.

 

16. Disconnect the 8-pin connector on the DRACC, be careful as the bottom left pin does stick out. It does not have a wire leading to it. Be careful as this unit is heavy for its size and has sensitive coils on the inside.

 

17. Rather than disconnect the vacuum lines, I grabbed an empty coffee can and placed the DRACC on top. This way nothing can damage the coils and it is being supported, not hanging by the vacuum lines.

 

At this time, you will want to remove the dash pad assembly. I have removed it several times. I will include a separate write-up for removing the dash pad.

18. It is at this time I removed the upper HVAC duct Center outlet duct from the dash. It takes a little patience to work this past the HVAC box on the firewall. There still isnt a lot of room.
19. Using a 7/16 socket and 6 extension, remove the lower bolt holding the HVAC box to the firewall.

The first picture is of the dash pad removed, you can see the center outlet duct, half of the outlet is connected to the vent above the radio. The second picture is of the center outlet duct removed. The last picture is for step #19.

 

20. Using the same socket without the extension remove the nut on the engine side of the firewall from the A/C Evaporator Box. That is the stud that is on top on the inside HVAC box.
21. Remove the 5/16 hex head screw that holds the defroster duct onto the HVAC box. This is on the inside of the car, it is pretty obvious. But I'll include an additional picture with an arrow pointing to where the screw came from.

 

22. If you have a service manual refer to 13-84 (per the 1971 manual). There you will see that defroster duct is held to the dash assembly by four metal tabs. Use a pair of needle nose plies to twist them straight and allow the defroster duct to drop down. The furthest tab over on the drivers side is the most difficult. I spent about an hour and a half trying to get it to bend. I ended up using a pair of mini needle nose plies and fishing my hand up to the tab from the bottom. I doubt this will work for anyone with a normal sized hand.

This last picture is of the defroster duct assembly removed.

 

23. Using a 7/16 deep wall socket remove the two nuts holding the Heater and Defroster Assembly to the firewall. These are on the engine side of the firewall. The arrows point to the two nuts.

 

Here would be the first step to removing the dash pad.

24. Remove the (6) screws holding the lower instrument panel onto the dash using a #2 philips. This is the plastic panel on the driver's side that has a small chrome vent in it, below the steering column. The panel is pictured here, you can see two of the holes for the screws.

25. Using a ” socket, remove the (2) hex head screws holding the lower instrument panel onto the dash and remove panel.

 

26. Using a #2 philips screwdriver remove the screws holding the dash pad to the dash. One is directly below the headlight switch on the drivers side, One is on the opposite side underneath the radio, four are on the top of the instrument cluster. Two are by the speedometer cluster, one is above the right side HVAC duct, and the other is about the wiper switch.

27. If your car is Equipped with Automatic Climate Control, remove the hose and connector going to the thermo switch & sensor in the dash pad.

 

28. Pull on the heater and defroster assembly. It will come out with some resistance. That is usually from the grommets on the heater core inlet and outlets that are in wedged in the firewall. Be sure not to pinch any wires or vacuum lines when your remove the assembly.

Below is a picture of the assembly removed.

 

29. Using a 5/16 socket, remove (2) hex head screws holding the base of the heater core and (1) additional screw at the top. Napa had the heater core at the warehouse. And it was inexpensive.
30. Again, I cant stress this enough. Clean everything, every surface youll thank yourself later! Simple Green works best for me. No citrus or fragrance left behind.

 

on my Riv all of that stuff is under my hood. I just replaced the core last week and it took less than an hour. 5 bolts and a few screws/ cable connections andit was on my bench.Your project looks like a nightmare for the mechanicly challenged. On a pos not your step by step and pics are awsome:TU:

 

Great tech thread !!!