I finally have enough heat to cook an egg!
I had decided to take the thing to a dealership to get it fixed. After reading through 37 pages of posts last night, today I decided to try ONE LAST TIME to resolve this.
Several months ago I used the Prestone radiator flush and left it in for 3 days while I drove it. I then flushed it completely for almost an hour through the radiator cap using a fitting in a flush kit. No change. After reading extensively last night, I decided it HAD to be a dirty heater core.
So I disconnected both heater hoses at the block and, using the hose, flushed extensively in both directions. I then blew (by mouth) into the inlet hose to clear most of the water from the heater core. It must not hold much since I only poured about half of the bottle of Prestone flush directly into the inlet hose while elevating it. I let it sit for an hour and then flushed it with a hose for about 15 minutes. I then repeated the whole process with the other half of the Prestone bottle and then filled the hose with antifreeze and reconnected them. Burped the system and drove it for 20 minutes. It was warmer, but didn't really kick in until I kicked in the passing gear a couple of times. Then the heat really kicked in and continued even at low speeds. While flushing the heater core, I collected the effluent and there didn't seem to be very much "junk" being flushed. But it worked!!!
Thanks to all who offered advice. I guess it helps to be persistent!

 

I've owned many vehicles but never had a heater core not put out hot air. It seems that this is a problem with a lot of Jeeps. What's different about Jeep heater cores?

 

Finally information that is helpful. Just bought 2001 sport with 150,000 miles and temp today was -12 so I thought "crank the heat up" ...luke warm air! Defroster hardly removed any frost.
***** seem to control fan speed, etc. No check engine codes on dash. Temp **** only seems to make minimal difference from low to max hot.
I'm thing now it is blend door related. Will check out movement of shaft tomorrow and if I determine doors maybe broken off will cut thru housing and replace doors (Heater Treater). Not going to go the remove dash avenue for fix!
Hey anyone know why all door repair videos are about Jeep Grand Cherokee. I could find none on Jeep Cherokee (Sport).
Looks like end of week we will get above 0 for a day or two.

 

Got reply to
1. check heater hoses to see if they got hot. Yes both do
2. check for milky coolant (blown head gasket). Antifreeze looks good no foam in radiator cap or expansion tank
3. Have not checked function of blend motor yet. Looking for directions to remove glove box to check and see if doors opeating by moving from AC to heat with ignition in run position.

Will consider the heater core flush if I am not finding other cause for poooooor heat. Tomorrows temp -2.

Found out Cherokee Sport does not have diagnostic code function for blend doors as the Grand does.

 

Damn I wish it was that easy I replace my heater core and still cant figure out why I have crap heat.