70 Sport Fury Heater core removal

Modelbuilder

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Hi everybody!
I have a 70 Sport Fury 383 2bbl with AC.
The previous owner disconnected the heater lines.
Found the heater control valve body was cracked. Purchased a nos one.
Then I thought that I should remove the heater core / AC exchanger combo and get it cleaned because evaporated coolant will crystalize.
That could break loose and then clog up some other component.
Can I just remove the box under the dashboard or do I need to remove the cover on the firewall under the hood?
 

Modelbuilder

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Hi everybody!
I have a 70 Sport Fury 383 2bbl with AC.
The previous owner disconnected the heater lines.
Found the heater control valve body was cracked. Purchased a nos one.
Then I thought that I should remove the heater core / AC exchanger combo and get it cleaned because evaporated coolant will crystalize.
That could break loose and then clog up some other component.
Can I just remove the box under the dashboard or do I need to remove the cover on the firewall under the hood?
Now I feel stupid. My car is a 71. I have been looking at so much stuff online to figure out what I needed to do to repair it. I put the wrong year of my car in the question.
 

Davea Lux

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Hi everybody!
I have a 70 Sport Fury 383 2bbl with AC.
The previous owner disconnected the heater lines.
Found the heater control valve body was cracked. Purchased a nos one.
Then I thought that I should remove the heater core / AC exchanger combo and get it cleaned because evaporated coolant will crystalize.
That could break loose and then clog up some other component.
Can I just remove the box under the dashboard or do I need to remove the cover on the firewall under the hood?
This job is a major PIA. Download and read the section in the FSM. Download is free at www.mymopar.com, manuals are in the tools reference section. You should really replace the heater core while you have the unit out. You must remove the inner cover under the hood and the air box under the dash to service the heater core. The glove box, heater control, radio and ash tray need to come out to gain enough room to rotate out the air box. The wiring harness will also need to be propped up to get it out of the way. Be careful not to damage any of the vacuum motors as they are getting hard to find. You might consider having you unit pressure tested prior to pulling it out. If it tests ok, run it until it fails. The A/C will need to be discharged and evacuated as part of the process as well. The A/C evaporator does usually go bad as long as the hoses have not been disconnected and the unit exposed to the air for an extended period. They also fail if critters have built a nest and pee'd on the evaporator. '70-'71 used the same heater core. You will also need to source a new air box gasket set as part of the repair process as the foam gaskets are always bad when the unit is taken apart. If you A/C has not already been converted from R-12, this will probably need to be done at this time also.

Dave
 
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Big_John

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As said, PITA to remove.

Why not just flush the core? A half hour with a hose will save you hours of aggravation and cussing.
 

Loadrunner

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Way overthinking. Flush the core as said, use Prestone Super Flush or similar if you feel the need to, follow directions for best results.
 

Modelbuilder

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You guy wouldn't know what is going on here would you?
This hose comes through the firewall and is screwed to the heater box and plugged at the end.

hose 01.jpg


hose 02.jpg
 

Davea Lux

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That is what is known as a "field service modification." Unit probably had a clogged condensate drain or a leaking heater core and somebody added this as a way to keep fluid off the carpet. Doubt it worked, but you gotta try.

Dave
 

Modelbuilder

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I am guessing with this half A$$ repair I am going to pull the heater out as my carpet and floors are good. Iv'e had a coolant leak before and don't want that in the car.
 

CBODY67

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As a default mode, IF that rubber hose was supposed to catch the condensate due to a leaking case gasket (which was common on those cases, best I can tell) AND/OR the car had solid vinyl factory floor mats in the front floor areas, the carpet and pad could be damp and you not know it. I discovered this on my '70 Monaco after I'd had it for a while. I took the rh floor mat out and it was damp on its back, as was the carpet.

After I got to looking at things, the case gasket is something like an open-cell rubber, which is fine. The case halves are held together by slip-on clips and screws. All sounds normal so far. But the rubber has enough surface tension (on its sealing surfaces) such that there is a gap on each side of the clips, from which condensate CAN escape (rather than going out the drain tube). The old-line Chrysler service manager claimed, too, that they stopped using a drain pan under the evap core, so that the condensate went directly to the bottom of the case and then out the drain. Those gaps by the clips gave it another route "out", it seems. Hence, the split heater hose contraption you have.

There CAN be a better way to keep the hvac box halves together, I suspect. Like using prevailing-torque flange-head nuts (with a floating captive washer, possibly) rather than the slip-on nuts the factory used. Plus putting a skin-coat of black silicone sealer on all sides of the gasket prior to installation, installing it after it cures a day or so.

Additionally, in some humid environments, the outside of the hvac case CAN sweat, with that moisture falling on the floor beneath the case.

I concur with the "use it until it leaks" orientation for the heater core. When you are flushing it, flush it in the normal direction of water flow through it (which is in the heater hose routing image in the FSM, usually. I was flushing the core on my '67 Newport, getting a clear flow out of it, THEN I decided to do the "reverse flush" operation, which then sent things backward and plugged the core. Whoops! And it's still that way, years later.

In the mean time, DO shop around for a quality heater core and evaporator core from a good vendor! Sooner or later, you'll need one or both.

Just some thoughts and observations,
CBODY67
 

Modelbuilder

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Thank you for all of your incite on this subject.
Now that I have an explanation for the red hose installation. I think I will flush the system install the control valve and get on the road.
 

furious70

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Pita if you do need to remove but you do not need to take the firewall cover off to get the box out. Radio and controls stay put as well. You need to peel the carpet back loosen the console if you have one. Glove box comes out, loosen the dash frame on the passenger side and it'll come out
 
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