Heating issue

[jjej5too]

Aquired my 3 Jeep about a month ago and I'm scratching my head. It's a 2002 KJ with 225K which had heating and cooling issues and was headed to the bone yard... I intercepted it because I'm a softy for Jeeps and the body / interior is perfect. Anyways my issue: KJ was overheating due to lack of general maintenance and heat in KJ only gets to 100 degrees in 50 degree weather, coolant was original & nasty... Coolant just trashed and ineffective so I decided to strip and replace entire system: New Rad, Pump, Thermo, Res Tank and AC condenser (For air flow) Vehicle doesn't overheat anymore. PROBLEM IS: I tried saving the core and increase its output of heat by #1 Unhooked it from system #2 flushed it with water in both directions for 3hrs, changing core sides every 15min, no plugs, water coming out prestine. (Still at 100 degrees) 2nd Thing I tried was blew dried the core with 18# air and filled with "Tide" let it sit 3 days (Got idea from an old race car driver) flushed out core until clean (No change 100 degrees still) 3rd thing I did was dried out core again and filled with Drano let sit 30mins and flushed core once again. (No change still at 100 degrees) Now I got frustrated so I decided heck with it... I'll CLR it knowing perfectly will it eats aluminum and directions say not to use it on rads, and not to use it in it pure state for more then 2mins. I did this procedure 6 times, Dry core with 18# air, fill core with CLR, wait 5 mins, Flush with water 15mins, Blow dry core with 18# air and repeat. (No change still blows 100 degree air) Min spec at 50 degree temp is 135 at vent. I'm assuming the answer is yank the core? If so, I would appreciate a link to 02 KJ dash removal or even better a short cut to replace this crazily hidden core. Thanks Eric

 

[jeepguy4276]

I had the same issue and replaced the heater core. it's a big job. Not so difficult as tedious. There's a lot, a lot of nuts bolts screws and fasteners that need to come out. Once that's done it's pretty easy. It's a full day project.

Your other problem could be your blend door actuator. Since you are producing heat, just not enough, it could very well be that the blend door is not fully on heat. That would mean the heat at the vents is cooler than it should be. The heater box has to come out for that to fix it right. Just a thought on another issue you could be having.

No matter what you do, make sure you are using HOAT coolant. The others can harm the system and don't seem to produce the same heat and cooling.

 

[LibertyTC]

Normally I would replace with new Mopar thermostat as well.
After systems been apart, you may have to bleed the air out of system, top rad hose has air bleeder screw.
Did you initially run it for a while with the reservoir cap off & add to cold line? Each morning for a few days, I had to add HOAT to cold line, then start it.
Is the blend door working in all functions, dash, center vent, floor etc?

 

[jeepguy4276]

The blend door is whet selects between hot and cold air or anything in between. It does not effect what vent the air comes out of. Ones electric and one is vacuum.