How to: Replace rear heater core without conversion kit

Mooseman

Original poster
Moderator
Dec 4, 2011
25,580
Ottawa, ON
So my rear heater core started leaking. Looked for the parts and the core itself was just $88. But looking at the description, it needed a conversion kit at $234! GM, in their infinite wisdom, decided to change the way the rear heater core is connected. It went from a block style connector, similar to A/C connectors, to the Quick-Loc type, which is used everywhere else in the truck. But there was no way I was going to pay that much for that so I looked at the new heater core and figured out how to change it without the conversion kit.

I basically just used Quick-Loc connectors to connect to regular heater hose. The old hoses cut off from the old connector weren't long enough to reach the new connectors so had to extend the hoses with connectors and extra 5/8" hose.

For full instructions on how to do this, just get a hold of the manual. Just a few notes on the installation:
- The entire rear heating system has to be removed to remove and install the heater core. That means also disconnecting the A/C lines. Some have been able to do this without disconnecting the A/C by lifting it high enough but would require the help of a second person to hold the HVAC unit up while you pull and install the the heater core.
- My A/C connector was so corroded, it wouldn't separate so I just cut it off. No more rear A/C and I'll have to block off the rear lines later so I can have front A/C again.
- I used duct tape to block off the resulting hole left by the missing block. A better thing would have been expanding foam or a piece of flat rubber.

If you have any further suggestions or tips, please post them up.

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RadsTBer

Member
Aug 17, 2013
2
My heater core is also leaking. I would rather keep the A/C than the heat. I'm thinking of removing the heater core and just plugging the lines. Is this possible ? And what is involved with disconnecting the A/C lines in the back ? Is this going to depressurize the whole system ? I've never done any A/C work before.
 

Mooseman

Original poster
Moderator
Dec 4, 2011
25,580
Ottawa, ON
You wouldn't need to disconnect the A/C lines. All you need to do is cut the heater hoses and splice them into each other using a hose splicer like one I used, bypassing the heater core. No need to remove the heater core or disassemble the rear HVAC. All that will happen is that the coolant will circulate through the hose back to the front.

As a side note, I haven't been able to use my rear heat because my actuators have been dead since the day after I replaced the heater core :mad:. And my rear A/C has been permanently blocked off because of the above. I don't miss either although I may be replacing the actuators before this winter.
 

RadsTBer

Member
Aug 17, 2013
2
Thanks this is going to be easier than I thought. Except for the fact that I already removed the inside plastic trim, darn. Well I have some 5/8" hose couplers. Is that the I.D. of these heater hoses ?
 

Mooseman

Original poster
Moderator
Dec 4, 2011
25,580
Ottawa, ON
5/8" is the correct ID.
 

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