TylerW
Well-Known Member
I had to replace the heater core in my 1975 Duster recently, and I thought I would share the procedure as outlined in the 1975 Chrysler service manual:
First off, I have read on here how much of a pain this is to do, because you must discharge the AC and remove the entire HVAC unit from under the dash.
Well, that's not at all necessary. The Chrysler procedure instructs you to remove only what is needed to access the heater core, and here's how:
1. Remove the battery neg. cable, and remove the heater hoses from the core connections.
2. Unbolt and remove the heater tube plate between the heater hose connections at the firewall.
3. Inside the car, remove the radio, ashtray and frame and the glovebox liner.
4. Remove the plastic air-conditioning duct from the lower edge of the dashboard.
5. You then will see a flat plastic piece facing the rear of the car. Remove the visible bolts and also the 2 on the top of the box, one about center and the other just behind, and attaching, the rh defrost duct.
6. Remove the 2 bolts holding the defrost vacuum pot device on the lower left and move it out of the way.There is a second duct behind the bottom of the flat plastic piece. It has a few bolts across the bottom and 2 at each end. Remove it and the flat piece and set them aside.
7. Next is the distribution housing. This is located directly forward of the ashtray opening and is retained with several bolts. There are a few across the bottom, one at far left, one on the far right and 3 across the top.
The top ones aren't bad once you find them in the debris is insulation.
8. Work the distribution housing loose and slid it out.
9. The heater core will be visible..simply work it and the seal out and remove.
10. Installation is the reverse of disassembly. Now would be a good time to replace wiper arm seals and pivots.
As you can see this is more simple than removing the entire box and dealing with the ac BS.
First off, I have read on here how much of a pain this is to do, because you must discharge the AC and remove the entire HVAC unit from under the dash.
Well, that's not at all necessary. The Chrysler procedure instructs you to remove only what is needed to access the heater core, and here's how:
1. Remove the battery neg. cable, and remove the heater hoses from the core connections.
2. Unbolt and remove the heater tube plate between the heater hose connections at the firewall.
3. Inside the car, remove the radio, ashtray and frame and the glovebox liner.
4. Remove the plastic air-conditioning duct from the lower edge of the dashboard.
5. You then will see a flat plastic piece facing the rear of the car. Remove the visible bolts and also the 2 on the top of the box, one about center and the other just behind, and attaching, the rh defrost duct.
6. Remove the 2 bolts holding the defrost vacuum pot device on the lower left and move it out of the way.There is a second duct behind the bottom of the flat plastic piece. It has a few bolts across the bottom and 2 at each end. Remove it and the flat piece and set them aside.
7. Next is the distribution housing. This is located directly forward of the ashtray opening and is retained with several bolts. There are a few across the bottom, one at far left, one on the far right and 3 across the top.
The top ones aren't bad once you find them in the debris is insulation.
8. Work the distribution housing loose and slid it out.
9. The heater core will be visible..simply work it and the seal out and remove.
10. Installation is the reverse of disassembly. Now would be a good time to replace wiper arm seals and pivots.
As you can see this is more simple than removing the entire box and dealing with the ac BS.
