I've not done anything with the jeep except put 35k miles on it. It's the girlfriend's daily driver/ hiking getaway vehicle. I'll have to check her coolant tonight.

 

I learned this weekend that the cooling system on these things doesn't like any air in the system. It must be completely full and the best way to do that is with those special funnels that allow the system to burp and refill itself without getting more air in the system. This one fits our Jeeps https://www.amazon.com/EPAuto-Radiat...35745566&psc=1

 

I just went through this on mine- round 1 checked the blend door, round 2 I flushed the system.(got heat back) and now round 3 I flushed the system and cleaned out overflow tank which had about 2" of sludge in the bottom.

It wasn't like I had no heat but it wasn't ever really hot, and then once it did get up to temp it would be better. After this round the heat is like it was when it was new again- still a fair amount of crap in there, probably going to drain/flush the entire system come spring but at least I can be comfy on the way to work