Got a problem with defrosting. Here goes. Windows defrost about half way. Heaters hot on both sides in all ranges. No wet floors or outside anywhere. Ac works great and just changed the compressor. Everything is charged up. Both lines to the heater core are hot to the touch. One slightly less then the other and I've tried flushing it also.

 

Not having a wet floor doesn't necessarily exclude the possibility of a core leak. Also, there is a difference between defrost, and defog...Defrost uses your engine heat to warm the windows and melt ice/frost. Defog uses the AC compressor to remove moisture from the inside of the windows caused by your breath, and humidity in the air that is condensing on the window. Defrosting should be done with the temperature selector on hot, defogging with the selector on cold.

Flushing your coolant system won't help anything unless your core has a blockage (it apparently doesn't, if both lines are toasty and the heater blows nice and hot). My guess is you have a tiny leak in your core. Have you tried some Bar's Leak or something? If it's a small leak that'll probably plug it and fix you problem. If not, you'll have to pull the core and repair/replace it.

 

Sometimes the foam seals on the flapper doors get old and start falling off. The pieces can wedge themselves in the doors keeping, say, a door to the floor vents open not allowing full flow to the windshield vents. I’m just throwing stuff up in the air though.

 

im leaning more towards what ZCR1 says, if you had a leak in the heater core you would be low on coolant (even a pinhole leak will loose fluid over time) also stop leak causes more problems than it solves, if you have a problem you are better off fixing it right, the stop leak is just as likely to clog the radiator as it is to fix the leak

 

Yep, always better off fixing it the right way (repair or replace core). I don't know how much trouble it'll be to R@R the core in a Durango, but in some vehicles it's better to try a little stop-leak and see what happens, than spend as much as 6 or 8 hours (or several hundred bucks) changing out a $35 heater core right away.

I've never had a radiator get clogged using the stuff, though I suppose it's possible. It's my understanding that it doesn't build up unless there's a leak. I've used it several times and never noticed any problem. Though if it were me, I'd use the liquid, not the pellets. It seems to form a better "plug" and stop the leak completely more often than the old pellet stuff. I've heard the "Copper seal" is even better, but haven't tried it myself.

 

Ya I was hoping to get around that. Not a very fun task to tackle. Thanks for all the info. I appreciate it

 

yea the heater core in these trucks is a PITA since you have to pull the dash, definitely an all day job

however i would NEVER put the stop leak into the system except in an extreme emergency.

 

Okay its a defog problem not a defrost problem just getting that straight. Windows in the whole inside fog up and windshield only partially defogs. Probably the heater core just getting more opinions before i tear into that sob. Have a faint smell inside also. Dont smell it with the ac. If that matters. And i didnt say but is a 4.7 durango. And foam seals on which flapper. In the dash? Is there a way to check without taking the dash totally out?

 

And ive heard something about an ac evaporator. Not sure what that does or ? One other thing I forgot about but it stopped as far as i can tell once i changed the compressor. But I can see a foggyness coming out of the panels when I had it blowing if that helps anything

 

Jester, if there is actually a fog coming out of your vents, your heater core is probably leaking. It's odd that you don't smell coolant, though. If your core is leaking, you should be smelling it in the cab. Faint, maybe, but present. Especially if it's enough to fog all your windows except the windshield where it gets enough warm air to raise the temperature of that area high enough that moisture can no longer condense (dew point).

Sharpshooter....I think "extreme emergency" is putting it on a bit thick, really. I've used different types of leak stop for many years, and haven't seen a radiator clogged, or coolant system damaged from one yet. Not to mention how easy it is to remove from your system completely with a simple drain, flush, refill. Maybe my comfort level for using this sort of thing is significantly higher than yours, as I've been doing my own mechanic work since I owned my first vehicle (a '68 GMC truck, by the way) and don't mind tackling anything that comes along, or maybe you've had bad experiences with something I haven't. But rather than "extreme emergency", I'd say instead "tight spot". For example, if a guy has a heater core that's leaking and which will take an entire day to replace, or more if he isn't experienced in that sort of thing, and he just can't spend the time. Or maybe he has to pay someone to do the job and has to save up cash to pay for it....

[EDIT] I intended to mention this before I posted it but forgot....General Motors has been using the stuff in nearly every vehicle it builds, since back in the late '70s...not Bars leak brand, but the exact same material. The difference is that bars leak puts theirs in a soluble oil so it's easier to pour into the radiator. And so far as I know, there's never been a claim of a coolant system damaged by the stuff, though of course this doesn't mean it's never happened....only that if it has, it's rare enough I've never heard it mentioned.

In any case, if it were mine, I'd feel perfectly comfortable giving the stuff a try in hopes that it would seal it off long enough for me to plan the work ahead. Unfortunately, after hearing that it's fogging up all windows in the vehicle, I wonder if the leak isn't more than the stuff will plug even temporarily. I'd still give it a try, though, if it would put off the necessity of pulling the core for a week or three. In fact I did, in my '76 Matador a few years ago while I tried to find a replacement core for it. It didn't seal completely in my case, and it wasn't leaking bad enough to fog the entire interior, just the windshield, and the wings mostly. Never did find one and ended up having to fix the one in it instead.