Heater core failure

Digitalchaos

Registered User
Earlier I started the car after a night of rest to run an errand. As I was about 5 minutes into my drive, haze starting misting onto my windshield and a strong smell of coolant took to the air. Next, some white smoke started emitting from the passenger side engine bay. I drove to my destination and popped the hood. I found what looked like a round black plastic outlet nozzle on the lower passenger firewall dripping coolant to the exhaust. First I thought perhaps a hose came off, but after looking around I realized there was none. Next I thought about my heater core, and looked inside near the floor vents to find drops of coolant. Hence I realized my heater core had failed, after detecting a faint smell of coolant for weeks inside the cabin.

First, I would like to know what this small plastic nozzle is. Is it some form of a drain or air inlet for the HVAC box?

Next, I am considering either bypassing the heater core, or replaing it through an alternative method I came across since I do not have the facilities to dismantle my dashboard. The alternative method I think I happened upon involves removing the heator core through a white 'access panel' on the left front of the HVAC box, behind the dash. It seems this panel can be accessed by removing the glovebox.

The access panel can be seen in this picture: http://www.sccoa.com/forums/attachment.php?attachmentid=5327&stc=1

And I located the information in this thread: http://www.sccoa.com/forums/showthread.php?t=41109&highlight=heater+core

It was stated however that a foam tape used to seal the heater core would be destroyed through this method. What exactly does this foam tape seal, is it important, and can an improvision be made?

Your help is appreciated as always.. If I am able to sucessfully replace the heater core through this method, I will attempt to create a writeup to greatly ease the difficulty of this task in the future.
 
Digitalchaos said:
First, I would like to know what this small plastic nozzle is. Is it some form of a drain or air inlet for the HVAC box?.
The tube which is poking through the firewall is the condensate drain for the A/C.
Digitalchaos said:
The alternative method I think I happened upon involves removing the heator core through a white 'access panel' on the left front of the HVAC box, behind the dash. It seems this panel can be accessed by removing the glovebox.

It was stated however that a foam tape used to seal the heater core would be destroyed through this method. What exactly does this foam tape seal, is it important, and can an improvision be made?
That white thing in the pic is actually the end of the core itself. The panel which covers it is black plastic. It is possible to pry the thing out of the hole w/o removing the dash but its tightly crammed in there by foam which you'll shred when removing the core. No biggey.. clean out what you can. All the foam does is seal the core so that the air passes through it and not around it. You might be able to use the RTV sealant to seal it up but of course it'll be really hard to pry it out the next time... You might consider using a non-hardening sealant. To deal with the big foam chunk at the firewall, bend the tubes together both when removing the old one and installing the new one. Then adjust them back once its installed. :)
 
Thanks for the info TbirdSCFan. Myself and a friend thought the foam might be for that purpose, and I saw the plastic panel covering the core.

I am having trouble discerning the foam near the firewall you mentioned however. Is this simply more of the sealing foam for the airflow, and are you saying it will get in the way of the tubes? If nothing else, I suppose I will know when I remove the core.

Lastly the drain for the A/C. Is it simply draining from the airbox I assume then.. which would mean the HVAC box is designed to be filled with water? Mainly wondering because I am thinking of the fact that it is likely filled with coolant.


Edit: Should I be concerned about any ground straps which may be attached to the heater core inside the HVAC box? I intend on adding a new one via the TCCOA info here
 
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Digitalchaos said:
I am having trouble discerning the foam near the firewall you mentioned however. Is this simply more of the sealing foam for the airflow, and are you saying it will get in the way of the tubes?
If you push in from the engine compartment by the aluminum tubes, you'll feel the foam. Its a big hunk of foam rubber. Because of the angle the tubes make, its nearly impossible to push them back through it, so you change the angle of the tubes. ;) :D

Is it simply draining from the airbox I assume then.. which would mean the HVAC box is designed to be filled with water? Mainly wondering because I am thinking of the fact that it is likely filled with coolant.
The drain tube is for condensation from the A/C evaporator only. Unless there is a leak, there should never be coolant coming from it.

Should I be concerned about any ground straps which may be attached to the heater core inside the HVAC box? I intend on adding a new one via the TCCOA info here
I'm not aware of any ground straps connected to the core or the blower motor, but I haven't read the article either :)

Edit: Just read the article and I can tell you its a good idea and worth the extra effort. You can skip the voltage checks, assume its needed, and just add the ground straps. According to the article, adding any ground wires can be done in the engine compartment.. nothing is needed inside the case itself.
 
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Just Replaced My Heater Core

After DL'ing the instructions, I decided that I didn't want to **** with it. Took it to the local Ford Dealer. They have a **** HOT supercoupe mech. there. Final bill was just a tick under $750. Ouch, but not when you realsize that the entire dash had to come out.

68COUGAR
 
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93BLKSC said:
After DL'ing the instructions, I decided that I didn't want to **** with it. Took it to the local Ford Dealer. They have a **** HOT supercoupe mech. there. Final bill was just a tick under $750. Ouch, but not when you realsize that the entire dash had to come out.

68COUGAR
It can be done w/o pulling the dash.. just isn't pretty and results may not be as good.
If you remove the dash, remove the case, and split it open, you are able to reuse the foam and get a "good" fit when reinstalling. Unfortunately, it also means you have to have the A/C discharged, unhook the lines, and then pay to have it recharged again later. No real simple way to do this. Taking the dash out is a pain. I had to do it when replacing my leaky evaporatore core which is why I replaced my not-yet-leaking heater core at the same time.
 
Thanks again. If that drain is for the evap core only, I now know where the freon leak in my A/C is which is causing my compressor to fail. :D :rolleyes:

Can the Evap core also be removed in this way? Obviously the A/C system is no longer usable.
 
Digitalchaos said:
Thanks again. If that drain is for the evap core only, I now know where the freon leak in my A/C is which is causing my compressor to fail. :D :rolleyes:

Can the Evap core also be removed in this way? Obviously the A/C system is no longer usable.
If your evaporator core had a leak, you wouldn't have any visible evidence of it; once the freon or r134a hits the air its becomes a gas. They usually use an electronic sniffer or leak detector dye to find it.

You'll definitely have to pull the dash and the evap case to get the evap core out. Just leaving it in place as is doesn't hurt anything. One thing which might help is to take the blower motor out and vaccuum up the leaves at the bottom of the evap core.. that will help the air flow some.

If you decide to repair your A/C, let me know; I went through all that a while back and I can tell you what all I did to convert to r134. :)
 
Depending on the cost of components involved I may fix the A/C in the future. I would certainly like to for traveling comfort of passengers.

About the evaporator drain, how exactly does this work then? Does the evaporator condensate around the outside of the unit and drain into an area sealed from the heater core, or is it something else? Just trying to better picture what exactly has been contaminated with coolant for it to be flowing from this drain.

I have completed the bypass. I connected an air tank to one of the heater core hoses and blew the coolant through the other hose to clear out any remains. Only 1 or 2 drops of coolant entered through my floor heating vents. So where exactly did the coolant go, and why didn't it come in? Might there be a puddle somewhere in the HVAC now?

Both core hoses are simply exiting to the ground outside of the firewall.
 
The HVAC box is basically a large molded plastic enclosure that houses the Heater Core, A/C (radiator thingy) and a few baffles that change the path of the air either over the heater-core or A/C thing. I'm not sure how "directly" both radiators drain in the box, but as water collects on the A/C, it drops to the bottom of the HVAC box, and then drains out of the car through the firewall. In your case, b/c the heater-core introduced liquid into the HVAC box, it too drained out through the firewall.

Having swapped dashes before ( see post you refered to previously ) I can tell you that nothing is better than cracking open the HVAC box and giving it a really good cleaning. Also, you can then ensure that the Heater Core and A/C have good sealing around them so that you are maximizing the temperature of the air flowing THROUGH and not AROUND them. I don't remember right now what you said the year of your SC was, but mine was a '90, and under the cowl, there isn't much there to block the path of debris that can fall into and clog the HVAC box. This has a really bad effect on your level of air flow comming out of the vents. B/c the A/c is the first radiator that you see when removing the blower fan, and it also has more fins packed closer together than the heater core. So... any debris that fall into the HVAC get stuck on the A/C, (and IN the a/c fins) and pretty much cut the air flow to zip.

You mentioned that you didn't have the facilities to take out the dash. It doesn't require anything special, just 2 people (it's heavy and awkward) and a few screw-drivers and sockets.
 
Here's a picture of a HVAC box opened. I thought this might help.

HVAC%20box%20in%20half.jpg


-Rod
 
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