I was driving home from work one day and heard almost like a backfire, but it wasn't as loud, came from engine compartment, and didn't sound like an exhaust problem.

Shortly after from the passenger side dash there was a small fogging area collecting moisture. Now when I drive, especially when it's cold, the windshield fogs up, and using defroster either hot or cold it doesnt go away, and when i wipe with rag it seems to streak a bit like theres a substance (which would be consistant with coolant as moisture) there is also a smell i can't describe which I thought first to be oil but doesn't seem so strong.

A friend suggested to see if a hole formed in exhaust manafold, but I dont see exhaust in engine compartment. Also I seem to be loosing coolant. Seems consistant with heater core leaking. First should I replace both or just the front, and see, the hoses are hot and I do get hot air, except obviously if the coolant level is low. I have been checking frequently the coolant level to ensure I dont overheat and warp a head or something.

Anyone have a step by step on replacing heater core, I can get one at autozone for 30 dollars for front, so I don't see the harm in changing it out and checking if it resolves problem. I understand I must take dash off which I am sure is a pain.

Any ideas?

 

It certainly sounds like a coolant leak, but a heater core doesn't usually make a "pop"ing noise when it goes; it usually just quietly starts leaking. It is located behind the glove box, so you can look around there for traces of coolant leak.

My experience with a "pop" followed by fog in the cabin was from a radiator hose exploding. That was severe, and there was no way to drive the car afterward. In your case, I am guessing a heater hose has popped. Try to find it by following all the heater hoses under the hood to look for the leak.

 

A leaking heater core will cause the windshield to fog up.

It doesn't matter whether it's a car, truck, SUV, whatever.

Outside air is ducted thru the heater core into the plenum chamber.

Now..with a leaking heater core, you have coolant mixed with air.

Look on the passenger side toe board and floor for signs of dampness.

 

Certainly sounds like coolant leak, pressurise the coolant system with a pump. Safer than running the engine.

 

I don't know if it was a pop or not but until today, unless i start the fan it seems negligable. oday it seems more apparent even when the fan is off. I don't see water pouring out as if it was a ruptured hose, but would a ruptured hose even do that. I will be pulling the dash and replacing the front heater core, is the back core there too, because for 30 dollars id rather replace than pull the dash just to have murphys law come up and the core go bad 2 weeks from now. oes anyone have drawings or directions of pulling an aerostar dash, and will i have to mess with ac system or anything to extract old core.

 

You don't need to pull the entire dash to get at the front heater core; you can just remove the lower half of the dash and you should be able to get pretty good access to the heater box. You will have to remove the radio and equalizer, if you have one; there is a stud in that opening that part of the lower panel attachment hardware slides onto.

To remove the heater core, you will most likely have to break the plastic collar on the ends of the hoses that attach to the nipples on the core. Very few people have been able to remove those hose ends, even using the proper tool. Stick a flat blade screwdriver into the slot near the top of the collar and twist. This will release the retainer clip, which will allow you to pull the hose off. You may be able to reuse it with a regular hose clamp later. If not, cut off the plastic end and jam the rubber hose over the nipples, and use a hose clamp to hold it on. I used a ratcheting box end wrench (5/26") to tighten the hose clamp. You may have to reroute the hose to get enough slack, or add a new section of hose to extend it to the right length.

Be aware that the $30 heater core from Auto Zone is made from a generic core, and does not fit very well into the Aero's heater box. You will need lots of fillers like foam tape to keep it in place, and to seal it to the box.

The rear core is inside the rear HVAC compartment by the left side of the second row seat. I have never pulled it out before, so I don't know what it looks like.