Engine Can a heater core still leak if the ac is never in use?

dqureshi06 · May 28, 2024

As absurd of a question as it may sound to others, I just wanted to know if the heater core still functions and is prone to leaking even if the ac system is never being used. I noticed fluid on my passenger side carpet and immediately thought of heater core as foxes are supposedly notorious for these breaking down.

Noobz347 · May 28, 2024

Yes. The heater core and evaporator core are independent of one another.

You're already aware that hot coolant flows through the heater core. There is a restrictor stuffed inside of the inlet hose (remember this). Engine coolant flows through the heater core any time the engine is running. The heater [blend door] (operated by vacuum) mixes heater core air with cabin/outside air.

You have two options: Replace the heater core or bypass it.

Since you're in Virginia, I would suggest replacing it but doing the bypass until you have all your [collective stuff] in one sack to do the project. It's a weekend deal.

limp · May 29, 2024

Its a fair amount of work replacing the heater core, this coming from a first time doing this newby, but if you take your time and have some patience its not horrible... Now if you get into a " this begats that" ( like taking all of the surfaced rusted metal bracing off the back of the dash, cleaning sanding and painting it ) it will take a little bit longer.... Pictures really helped me put it back together..

AeroCoupe · May 29, 2024

This is a 6-8 hour job the first time if you are mechanically inclined. It's a well documented process that does not require completely removing the dash.

Here is how LMR does is and there is a lot of good info in there but its the loooong way:

This is pretty much how I did mine the last time and it took about 6 hours:

flynndawg · May 29, 2024

AeroCoupe said:
This is a 6-8 hour job the first time if you are mechanically inclined. It's a well documented process that does not require completely removing the dash.

Here is how LMR does is and there is a lot of good info in there but its the loooong way:

This is pretty much how I did mine the last time and it took about 6 hours:

this is some BS... !!! i did mine years ago and went with motorcraft... !!! to hell with pulling all that crap off... !!!

General karthief · May 29, 2024

First...... Is it really leaking? I mean coolant? Coolant has a distinct smell, and it's sticky to the touch.
It maybe the condensation drain. Bugs and crude get in there and stop up the drain hole. If the carpet/floor is wet check it out before tear'n the box out.
Just say'n.

AeroCoupe · May 30, 2024

Any way you chalk it up its a pain in the ass. Be sure that you have the pressure restrictor installed or you will stand a good chance of popping the new one.

Mustang Heater Core Flow Restrictor (79-04) E7VY-18358

Reduce the coolant pressure flowing into your heater core with this heater core flow restrictor for 1979-2004 Mustang!

lmr.com

Engine Can a heater core still leak if the ac is never in use?

dqureshi06

Member

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

limp

wrap a little cheese around it and its a done

AeroCoupe

lube between the nut and the face. I know my lubes

flynndawg

Member

Attachments

General karthief

wonder how much it would cost to ship you a pair

AeroCoupe

lube between the nut and the face. I know my lubes

Mustang Heater Core Flow Restrictor (79-04) E7VY-18358

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Engine Can a heater core still leak if the ac is never in use?

Member

Stangnet Facilities Maint Tech... Er... Janitor

wrap a little cheese around it and its a done

lube between the nut and the face. I know my lubes

Member

Attachments

wonder how much it would cost to ship you a pair

lube between the nut and the face. I know my lubes

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