Time for the Heater Box Rebuild

[mgm1986]

Next on the list was to pull the heater box for inspection and rebuild. The heater hoses were disconnected and bypassed under the hood so I suspected a leaky core which is exactly what I found. I also found the home of the mouse that I found inside of the drivers side stub frame. All throughout the car I have found remnants of mice/squirrels and their food stores.

A quick 12v to the blower motor confirmed it is still working although it sounds like some of the mouse house got inside the cage. Never worked on a heater box but I am planning to break it down and hopefully get it working again. Probably have some questions along the way but the seemingly hard part of removing it wasn't all that bad.

 

[live4theking]

What vehicle is this on? I see you have a 68 300, but it doesn't look like the one from my 68 NYer.

 

[Bruce Cobb]

Check with DMT for a gasket/rebuild kit.

Detroit Muscle Technologies, LLC Mopar & AMC muscle car restoration gaskets

 

[mgm1986]

What vehicle is this on? I see you have a 68 300, but it doesn't look like the one from my 68 NYer.

Yes, this is out of the '68 300, non-AC car (heat only). No idea if it is original but it certainly looks to be.

 

[mgm1986]

Check with DMT for a gasket/rebuild kit.

This company has tons of stuff for our C-bodies! Thank you for sharing! @Bruce Cobb

 

[Bruce Cobb]

Jim Fillmore (DMT owner) is a great guy.

 

[3175375]

Take your time. It’s not difficult and you will appreciate your diligence when you are done.

 

[mgm1986]

Heater box disassembled. Has definitely been apart before.

Both Vacuum actuators appear to be working as does the blower motor itself. It seems that one of the actuators actually cracked part of the box where it is riveted, likely due to something preventing the flap from moving (mouse nests!). Will inspect further after cleaning.

The resistors couldn't be simpler so I threw an ohm meter on to confirm my suspicions about resistance through each to control fan speed. A little cleaning is all they need.

Should be easy enough to clean and reassemble. Going to order the rebuild kit and start looking for a core.

 

[3175375]

Heater box disassembled. Has definitely been apart before.

Both Vacuum actuators appear to be working as does the blower motor itself. It seems that one of the actuators actually cracked part of the box where it is riveted, likely due to something preventing the flap from moving (mouse nests!). Will inspect further after cleaning.

The resistors couldn't be simpler so I threw an ohm meter on to confirm my suspicions about resistance through each to control fan speed. A little cleaning is all they need.

Should be easy enough to clean and reassemble. Going to order the rebuild kit and start looking for a core.




View attachment 630406View attachment 630407

I thought there were 3 actuators, but maybe that’s only on a/c cars.

I believe they are:

1. recirculate/ fresh air
2. Heat temperature blend
3. Defrost

One of these is only a single control (one vacuum input). The other two are dual control. No?

 

[D Cluley]

On a non AC car I believe the temperature blend door is just moved by the cable from the temp lever, no vacuum involved.

 

[mgm1986]

Yep, two actuators and a cable controlled flap on this box.

 

[mgm1986]

Thank you again for everyones valuable input on this step of the project!

Heater box has been repaired and reassembled. There were a few cracks in the fiberglass box that needed repair and some of the metal panels had rusted pretty badly from the leaky heater core that was removed.

I repaired the fiberglass cracks with reinforced resin and used POR15 to paint the rusty metal bits that were badly pitted. I used rust-oleum rust reformer on the less corroded panels and reinstalled everything using the kit from Detroit Muscle (great kit). New heater core from Rockauto, fingers crossed no issues with it. Seems like a quality unit and it holds pressure which is good news.

Going to wait to reinstall the box until I go through the wiring which will take time so I won't truly know if this is working correctly for some time. It seems like a very simple setup though so I don't anticipate any issues. Also need to repair or replace one of the defroster vents before reinstalling in the dash.

 

[mgm1986]

Does anyone know where to find a new or acceptable replacement for the duct work that connects the heater box to the fresh air inlet on the passenger side pillar? It is an oval shaped duct that routes fresh air into the heater core. It seems like it was a pretty heavy duty material.

In the attached picture I circled where this duct work connects on the heater box. This is the only thing stopping me from reinstalling the box.

 

[mgm1986]

I found a used one on ebay that is supposed to be in good condition. Fingers crossed!

 

[david hill]

I found a used one on ebay that is supposed to be in good condition. Fingers crossed!

If you still in need of parts for your duct work, try @Murry B Park in Tiffen Ohio. Family run operation, he may have what you need. @cbody.com is the on line sight.

 

[mgm1986]

Thanks @david hill . I reached out to Murray about a week ago for a cornering light assembly but never heard back.

 

[david hill]

Thanks @david hill . I reached out to Murray about a week ago for a cornering light assembly but never heard back.

W/ Murry be patient. the weather has been cold and now wet. Maybe ask for an update on the status of your part.

 

[3175375]

Did you get the fresh air intake hose that you were looking for?

 

[mgm1986]

Did you get the fresh air intake hose that you were looking for?

I did, found it used on ebay.

 

[3175375]

In reviewing this thread and finishing the rebuild of Elwood’s heater box today, I find a couple of things that are interesting:

1) your Non-A/C 300 has 2 actuators and one cable as described and shown
2) Elwood (68 Plymouth Fury II) is all cable driven (3)
3) Non-A/C Dodges (Polara & Monaco) were the same as Plymouth Non-A/C cars

It appears that the all Chrysler 300s (I don’t know about New Yorkers or Newports) were using the vacuum type control head that I’m familiar with because my 69 Fury (Shamu) has that style and non-A/C Plymouths (I know A/C equipped Plymouths used the vacuum operated control head) were still using the all cable operated control heads.

Interesting….

Non-A/C Chrysler:

Non-A/C Dodge Polara and Monaco:

Non-A/C Plymouth Fury: