Heater not heating hot enough. heater core not

do you smell antifreeze inside? if so replace heater core

not sure on your cherokee but often there is a valve in the heater hose line just as the water enter the heater core .. the valve is controled by the the selection of heat or cool .. those valves frequently clog up and need replaced ... you might also have an air lock in your heater core .. if air is trapped in there then it doesnt want to come out and it occupies a portion of the heating surface .. you can take the top heater hose loose with the engine running but not hot .. that will blead off any air in the core .. it will also show you if you have a clog .. you should have lot of water flow thru there with the engine running .. you may also have a bad thermostat .. if that the case then the engine wont get up to temperature preventing the heater from working properly ..

i don't know realy if there is a fuse (though i doubt it) but issues with heatting may be this will help.

If the carpet under the heater core is damp, or if antifreeze vapor or steam is coming through the vents, the heater core is leaking.
Remove it and install a new unit (most radiator shops will not repair a leaking heater core.
If the air coming out of the heater vents isn't hot, the problem could stem from any of the following causes:

• The thermostat is stuck open, previnting the engine coolant from warming enough to carry heat to the heater core. Replace the thermostat.
• There is a blockage in the system, Preventing the flow of coolant through heater core. Feel both heater hoses the firewall. They should be hot.if one of them is cold, there is an obstruction in one of the hoses or in the heater core,or the heater control valve is shut. Detach the hoses and back flush the heater core with a water hose. If the heater core is clear but circulation is impeded, remove the two hoses and flush them out with a water hose.
• If flushing fails to remove the blockage from the heater core, the coremust replaced.
  

If u have issues with heatting may be this will help.

1- If the carpet under the heater core is damp, or if antifreeze vapor or steam is coming through the vents, the heater core is leaking.Remove it and install a new unit (most radiator shops will not repair a leaking heater core.

1 - If the air coming out of the heater vents isn't hot, the problem could stem from any of the following causes:

• The thermostat is stuck open, previnting the engine coolant from warming enough to carry heat to the heater core. Replace the thermostat.
• There is a blockage in the system, Preventing the flow of coolant through heater core. Feel both heater hoses the firewall. They should be hot.if one of them is cold, there is an obstruction in one of the hoses or in the heater core,or the heater control valve is shut. Detach the hoses and back flush the heater core with a water hose. If the heater core is clear but circulation is impeded, remove the two hoses and flush them out with a water hose.
• If flushing fails to remove the blockage from the heater core, the coremust replaced.
  

Sounds like one of two things are happening. Either the hose going to the heater core (on the engine side of the dash) is leaking causing coolant to spray into the passenger compartment or your heater core is leaking which is causing the dripping from the passenger side of the dash. This would also cause a loss of coolant in the engine which would cause the engine to overheat and not enough coolant to get to the heater core to supply heat to the passenger compartment. Check your coolant level (while engine is cold) and refill it with a 50/50 mix of coolant and water after you tighten the leaking hose or replace the heater core.Then start the engine and let it warm up to operating temperature. Again let it cool down and then top off the radiator with the 50/50 mix of coolant. Do not under any circumstances open the radiator cap while the engine is hot.

Your heater core is clogged, leaking, and/or going bad. If it was anything else in the cooling/heating system, you would not have the antifreeze odor. The heater core is located under the glove box. I hope this helps and good luck.
Please remember to vote if this was helpful in any way. Thanks.

My 2005 impala had the same problem. Here's the answer. The heater core is plugging up. When you sit idling, the fluid movement is slow, therefore the junk settles in the heater core, still allowing enough fluid to get through to heat. When you drive it, the fluid movement is much faster, therefore sending the junk into the heater core, plugging it up. To check for this problem: Get engine temp up to normal, feel both heater hoses. If one is hot and the other one is cooler, fluid is not passing through. Take off both heater hoses at the top of the engine, blow out fluid with low pressure.(5 or 10 lbs.) Fill both hoses with the right radiator flush. (Some engines are aluminum) Let stand for 4 hours. Flush with new antifreeze. (I used a garden sprayer) Stick the sprayer end in the heater hose and tape tight. My vent temp WAS 100 degrees. After fix was 152!!

could be the temp blend motor not working. does the heat go from hot to cold or is the temp always the same?

U have leaking head gaskets, all to common on the 3.8 V6
My experience: 20 years as a Ford dealer mechanic, 10 years as a Ford certified Master Technician.

the heater core is leaking.