I will try that this weekend, although I think I got reemed on the purchase of this fine vehicle--- i got under it for the first time last night and everything is extremly rusted as if it had been under water for a while. tranny and oil pan are soaked so it looks like I have my work cut out for me. also there is a brown and yellow wire on the right side of the engine block (as you are looking at it from the front at the engine) that is cut and run into a switch in the dash I dont know what it does yet, any suggestions or thoughts??? thanks everyone for the help I am sure after I get started working on this one I will be here a lot

 

well, did the heater core flush this afternoon. and as everyone has been saying, it was the cure! heat blows like a big dog now! i didnt use compressed air though, just water, and no CLR either. just kept flushing back and forth both directions until water was clear, its amazing how much black nastiness comes out of that core! thanks everyone!

 

Glad you have heat now! I will just warn you though, if it starts to get cool again and not blow as hot, you may wanna flush again and use CLR to break up as much of the crud as possible. Either way though, enjoy the heat!!!

 

It didnt work quite the way it did in the video for me and the passenger floor got soaked??? but when I tried to see where the antifreeze came from nothing under the dash seemed wet. it is not leaking and once i cleaned it up it did not leak any more so oh well, anyway the thermostat was actually broken and once replaced my heat started working so the short answer is it is fixed...

 

I know this is an old thread. But I just wanted to comment that I tried flushing my heater core with compressed air and now my heat is hotter than ever. My heater core had been replaced just over two years ago. I talked my dad into helping me with this. He doubted it would work, said there shouldn't be anything clogging it. But one hose was running hotter than the other so we gave it a try. Turns out some gasket sealer had gotten dropped in there when we replaced the thermostat a year ago. The heat hadn't been run in the jeep after the thermostat was replaced so we didn't notice the lack of heat til this winter.

That video was perfect to go by, had no problems. We didn't use anything except compressed air and it did the trick for me.

 

A cheaper alternative to CLR is vinegar, it does take a little longer of circulating but it does work not to mention its cheaper. Use 50/50 mix of vinegar/water.

 

I have 2000 xj. Did the head, thermostat, clutch fan, water pump and new radiator. I flushed the heater core backwards and forwards I let some prestone coolant cleanser In it for twenty minutes and rinsed again multiple times. Did this all end of august and now as I fears still not hot enough. I am going to try using compressed air and see how much this helps. I will post back what I find.


So I finally have some time to screw with my jeep and will attempt to do the compressed air; but more reading and thinking has me wondering about the blend door. I dont know much about it but from reading it looks like although the fan is working in all 4 settings there may be a door not quite open/closed all the way? How do I access this?

 

i have a similar problem, with the luke warm heat i may try the flush had put a new tstat in it and idk about the door on mine. my heat worked good till i had a freeze plug blow out then i fixed that so idk if something got in it

 

Have you checked the coolant levels

 

it seems fine but i may just have a full system flush done at a shop idk yet