I have had it in a garage for a few hours this last weekend. So it would have thawed out. My heat felt good coming out, but as soon as the cold took over... Boom cold!

I will garage a few hours this weekend for sure!

 

Could it be that coolant is circulating only through a small part of the core, but not enough of it for the air to pick up enough warmth? Maybe a small amount of coolant is going in and out, which makes the pipes hot, but the main body of the core is blocked. Does that make sense? I'm know nothing of how the cores work, but it would seem possible.

 

Agree with that thought process too. Absolutely wonder that. Blender or core? That is the question.

Both require dash to come out. Jeep should have easier access to these things.

 

To burp it, first let the Jeep cool down completely.
Remove radiator cap.
Turn engine on and let it start to warm up without the radiator cap on.
As the engine heats up, the thermostat will open to let the coolant move through the system. As the fluid moves, if there is air in the system, you will see burps and bubbles. Fill the radiator as this is happening. Eventually it will stop and the water will start to rise because it is getting hot. Put the cap on and use the Jeep. Do this once again after it cools down.

 

Putting the front end up on ramps or parking on a steep hill while doing the "burp" helps get air out of the cooling system.

The heater core on JK's is above the radiator cap so it's difficult to get air trapped in the heater core out when it's sitting level.

 

"well every one i may have made a break thro. if you look at my above post youll see what i was thinking. well i took out the blower motor and i got to take a peak at the heater core. well it was covered in more crap that i can care to tell about. im about to take out the box and take that thing out and put in a new one. hopefully it will result in heat. ill keep yas posted."
------and this follow up...
"fixed. it. well mostly. i took out the heater box and the evaporater was covered in more crap then i imagined. plus it had leaked out all its freon. so i put a new evaporater in and a new heater core and i have heat now. nice toasty heat. the onle problem is that the blower motor does not work on full blast. it works on 1 2 3 but not 4. ill look into that next time i got the time. the way i saw my evap was covered in crap was by taking out the blower motor. three bolts on the engine side. then i looked in and i was able to see a crap covered evap. well if this helps anyone awesome. if not well its something to try. at least looking at the evap could help. the heater core cost me around 67 and i got the evap for 137. Jjust Empty Every Pocket. all in all with calling for parts and labor and what not i finished in about 6 to 7 hours. a decent sunday i guess. but atleast i have heat"
... this was about a 2000 xj so idk how much..if any.. pertains to you.. but I hope it helps.. the closest ive come to potentially having heat after weeks of searching threads..

 

Good news coming from red rekliner.....

 

Guys. I was victorious! My Jeep is HOT again!!!! Really HOT!

After trouble shooting, I narrowed down the problem to the core. I didn't want to take it out unless it was the last option. I had the system flushed by a mechanic, but I had a feeling they didn't do the core as well as they should have. So, I decided I would do it myself, even though it is only 30 to 40 degrees outside.

I went to Lowe's and bought a fitting that would allow me to connect my garden hose to the core hoses. It was in the Inside Lawn and Garden Department in the garden hose area. It was a cheap little fitting made of plastic. You would use it if you cut your garden hose shorter and needed it to connect to a water spout outside. I then went and got Prestone Radiator Flush and Cleaner. Everything I have read says stay away from CLR!

So, after I had everything. I let my Jeep cool off for about an hour or so. I then followed the core hoses from the firewall to the thermostat area. I detached both hoses, not at the firewall, but the other end by the thermostat. I put the plastic hose fitting I got at Lowe's into the end of the top hose going into the thermostat from the firewall. I proceeded to flush water through the core with the garden hose out the other hose leaving the core. I then switched to the other hose and reverse flushed it. (Hint: Used a small flat head screw driver and WD40 to get the garden hose fitting out of the hoses for the Jeep) I did this multiple times. Just kept flushing. I usually let water run for 2 or 3 minutes. I then blew the water out of the core with my mouth through the hose fitting in the top hose, keeping bottom hose detached so water clears, that goes to the thermostat. After the water was cleared, I buttoned up the bottom hose. I then put Prestone Radiator Flush and Cleaner directly into the core and connected the top hose back to the thermostat.

After this I started my vehicle and monitored the Engine Coolant levels. When safe I took to a slight uphill and "burped" the system like the previous helpful Jeeper's told me too.

I then drove around for a little while and suddenly it was like a burst of sunshine. There was heat. But, not Jeep heat. It was certainly way hotter than what I had previously. This made me determined to win and blast the core clean.

I decided to repeat the process again. Flushed the hoses. Blew it out. But this time, I changed it up. I read somewhere that white vinegar does a nice job cleaning a core. So, I kept both hoses detached and poured white vinegar into the top hose until I started to see it dripping out of the other end of the hose. I then set a timer for 30 minutes and walked away.

I returned and flushed the core a couple of times through both hoses using a garden hose. I wanted to make sure all the vinegar was out. I then blew the water out of the core using my mouth through the hose fitting on the top hose leading to the thermostat. After I felt good about it, I buttoned up the bottom hose and poured Prestone Radiator Flush and Cleaner directly into the core again. I then started the vechicle, monitored engine coolant, and burped it on the a hill. I then set up for my second test run.

By the time I was done driving (20-30 minutes), my heat was soooo HOT it was uncomfortable.

I will have to clear the Prestone Radiator Flush and Cleaner eventually, but I have heat. JEEP HEAT! My ride is sooo hot it is like sitting on the sun naked!

It was differently a blocked core that needed persistence and patience. I just directly flushed it like crazy both directions.

Now I am ready for some winter off-roading. I won't have to drive with a snowmobile suit, gloves, hat, long johns, battery heated soats, etc... I might have to just wear a speedo.

Thanks to all those who helped me out!!!!! I am thrilled.

 

It's good to see you got it fixed but it should be noted that the owner's manual suggests NOT using any chemical flushes in the system. I'm not sure why, but they don't recommend it.

Only a week to fix the issue, not bad.....not bad at all.

Sent from my DROID4 using Tapatalk

 

I think they are just being cautious. Prestone developed that cleaner not to be harmful, at least if you get it out of there in a reasonable amount of time. Not doing it would mean no heat and possibly inefficient cooling for the engine. Once the Prestone flush is washed out of there, some Zerex G-05 or Mopar coolant 50/50 mix will protect the cooling system nicely, for a long time.

I'm guessing the previous owner had it flushed and filled with less than desirable coolant, causing the problem in the first place.