Hi folks, new to the forum but not Dodge Durangos, I'm on my second one now. I bought a new one in 2001 and drove it several years until a divorce settlement. I bought a second one in August of 2018, a one owner 2011 Citadel (5.7L Hemi) that was like new, well maintained, and 94K miles on it. The past owner had most work done at the dealer (oil changes, recalls, etc) and had all records, so I know it was pretty well maintained. I travel a lot so the mileage has went to 131K until now. A couple of months after I bought it the radiator needed to be replaced, the work was done under warranty at the local dealership. After that, I noticed the engine temp would vary a little more than before, but according to everything I have read here it was still pretty normal. Over this past summer the AC slowly began to blow less cool air, and I hadn't used it in a little while until a recent trip to Florida two weeks ago. On that trip it wasn't blowing cool at all, and the compressor continually cycles so I can assume that the system is low on refrigerant. So I switched off the AC at the console. Now I am back here in Carolina, it was cold yesterday and I ran the heater. Of course on certain settings the AC compressor automatically engages, but not on the defrost mode. I was a little less than an hour from home when it stopped blowing warm air, the windshield fogged somewhat, and nearly every light warning in the dash activated. Let's see, the check engine light, the ESC warning, the ABS, the ETC, and then the message Serv AWD appeared. All the while the overheat engine fan was running wide open. The water temp bottomed out to 100, and the oil temp was around 120°. I limped back home while my wife looked online trying to make sure driving it wouldn't hurt the engine long term. I made it home and parked it for a while before starting it back up. The water temp immediately began to warm up like normal, the heater worked again, and all the warning lights went away except for the MIL check engine light. I took it to the local Autozone and had them check the code, said it needed a new thermostat. So I brought it home and replaced the t stat with a 203° t-stat, and topped off the coolant. Fired it up, drove around for a little while and all seemed well enough, though the temp did swing a little more than usual. Rechecked the coolant level, added a bit more and while the Durango was sitting there idling it overheated enough that I shut it down around 249° and let it sit. The radiator cap felt cool, so I turned it to the halfway release, and it immediately discharged a fairly large amount of coolant. Meanwhile the MIL has remained on.
All of that background leads me to where I am now, and I don't have faith that the new T stat was the entire issue (if at all), though the old one did in fact have some corrosion. I guess my first question before I take this to the dealership, would a low refrigerant level in the AC system have any effect on the heating system to contribute to any of this issue? Hopefully that is the case causing the slight window fog, and not a heater core going bad. The only time I have noticed any smell was after the dealership replaced the radiator last year, and the smell persisted for a good bit of the summer when the vehicle was first started. Any ideas?

 

The issue may be that there is air trapped in the cooling system. Search the web for a procedure on how to flush, replace and bleed the cooling system on a Durango. I found this on the web https://www.carcarekiosk.com/video/2.../flush_coolant

You don't need to do the flushing part, just the coolant adding and what they call "burping" to bleed out the air.

 

Thanks for the reply DDCREW. I know about the burping, and had done that when I initially refilled the coolant after changing the t stat. But I think I may not have gotten all the air out of it, I have driven it since with no issues. Time will tell.

 

The hemis have been notorious for having the waterpumps go fairly early so that may be something to keep in the back of your head going forward if you continue having overheat conditions.