'72 w/ A/C heater core seal question

[Tom L.]

It seems the source of hot air entering my duct system is the missing heater core seals. Dr. Rebuild's catalogue shows two, a "Core Tube seal" (Item G) and "Core pipe housing seal" (Item I). I have attached the info from his catalogue in a Miscrosoft Word document below.

I have two questions, can the Core tube seal (Item G) be installed without dismantling the heater core/evaporator boxes? And how far up the tubes does the Core pipe housing seal (Item I) get pushed up from the bottom? Thanks!!

[Robert S.]

Re: '72 w/ A/C heater core seal question

I replaced the heater core on my AC 74' about a year ago. Not a fun job. The housing seal is installed from below and can be done by removing the heater hoses from the core tubes . The seal fills the cavity through which the tubes pass vertically. I do not think this part was ever used by GM but is a good idea. I just pushed mine up so that it did not interfere with the hoses after they were re-installed. I do not think the vertical distance is important as it will seal the cavity space at any vertical location. The other seal, as I recall, is used to seal the tubes as they exit the housing into which the heater core is mounted. This seal can only be installed after the heater core housing is removed from the car. If you are at this point you might as well replace the heater core. It took me perhaps 6 hours of disassembly labor to get to that point.

[Tom L.]

Re: '72 w/ A/C heater core seal question

With your explanation of the process I'll only be replacing the lower seal. The core must have been replaced at some point and the seals not replaced. Fortunately it's not leaking, but with my luck it will be shortly after the new seal is put in its place! Thanks!!

[Dick W.]

Re: '72 w/ A/C heater core seal question

While you are in there check the operation of the doors. I rebuilt the heater box on our '72 and found ALL the doors out of adjustment.