Last couple of weeks I've noticed the faint smell of coolant off and on while I'm driving. I use the heat every day. Yesterday and today I had the smell plus the windows wouldn't defrost no matter how high I turned the blower on. I still have heat, but it gets less warm every day. I think it is the heater core. I don't have coolant dripping onto the floor yet... just waiting for that. It's a 97 Sahara.

Is there anything else I can try before I attempt to replace the core. I do most of my own work, but I'm definitely not a mechanic. From reading old posts, it looks like it will be a pain in the a**. I don't have a garage and it is 11 below zero outside right now. This forum is great, has helped me in all of my repairs over the years.

First, check the engine compartment for coolant leaks. Many times, the smell of leaking coolant in the engine compartment will make its way into the passenger compartment. Pay particular attention to the two hoses that go onto the tubes of the heater that go through the firewall.

I doubt that a coolant leak is what is causing your reduction in heating ability. If you were leaking enough coolant to reduce the heat, you'd be leaking all over the place, and the coolant level in your radiator would be low.

On the other hand, you could have a collapsed heater hose, or a partially clogged heater core. In your kind of weather, it's often hard to tell if the cooling system has lost some of its engine cooling ability, so other causes can't be reliability checked without test equipment.

If you plan on replacing the heater core yourself, outside in sub-zero weather, I'd try running a radiator flush in your sooling system for a day or so. That might open up any obstruction in your heater core. However, it may also make any leak more prominent. But, at least you'll then know for sure where it is.

If you determine that the heater core is bad, and you're going to have it replaced by a mechanic because of your cold outside air temps, I'd strongly suggest a radiator shop rather than a dealer. The radiator shops deal with that job a lot more than the average dealership, and it will probably cost you a lot less.

I'll check the hoses later today when it warms up outside a bit.

What do you make of the loss of defrosting ability? I had an old car that did the same thing, and it ended up being the heater core. It's almost as if the condensation on the windshield is more than just water (somewhat slimey when I try to wipe it off).

I'm trying to tackle this ASAP because I don't want to be stuck with absolutely no heat in the freezing cold. Also, the condensation on the windshield is bad enough that I have to wipe as I'm driving... not safe.

Loss of heat is most likely a GATE problem either a lectric motor opens and closes the GATE or as in the square headlight model wranglers, vacuum opens and closes the GATE.
Unless you have been way negligent with that Jeep the core shouldn't be stopped up.
As for smell.. if you can smell it then you will have a Sevier loss of coolant, and a wet floor.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

Can you explain the function that the gate serves? As I see it, it is either open or closed. Since the heat has been gradually getting cooler over the past few weeks, I would imagine that if it is the gate, it is only partially opening and closing. Is this a correct assumption? How do I check and fix it?

Also, are you saying I'm smelling something else other than coolant? I definitely smell the sweet smell of antifreeze. I checked the level and the radiator is full. The other tank is about an inch low... pretty normal.

Yea, the Jeep is well taken care of, but I've lived in NC (beach, salt, etc), CA (scorching heat), and now upstate NY (or should I say the North Pole), so the different climates have been hard on it.

The gate is operated by the TEMP control and opens and closes with the movement of that control. If it is a KNOB then the control is lectric.. If it is a slidy thingy then most likely the gate is vac controled.
I have seen them fail in many ways.. Some always open and some always partially open and others always closed..
That damn gate motor seems to be the weak link in most modern heaters.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

Although i agree with everyone does anyone think it could be just a simple thermostat problem since he's getting less & less heat?

i think it could also bejust the thermostat, that should be noticed by the guage if its working correctly, they're less then ten dollars too, its an easy change, he doesnt state that its blowing less and less he states that its getting less and less warm

hmm, lets see, slimy windshield, less heat, defrost not good,Id check out that heater core sounds to be the work of a COLD mouse looking for some place warm to make his bed.

Guys think about it a while... Even if the heater core was leaking it would put out HEAT! There is coolant flowing thru the core all the time. Unless the core is stopped up..which is highly unlikely in a modern core. So if no heat either the engine is cold.. which would be a thermostat, or the heater temp gate isn't working as designed..
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />