1999 sport 4.0 liter wrangler 6 cyl no heat

Jeep Liberty heater not blowing hot air Questions & Answers ...

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Jeep Liberty cars & trucks heater not blowing hot air questions and answers. Ask your Jeep heater ... My 2005 Jeep Liberty will not blow heat through ... properly.

jeep liberty 2002 heat problem/hvac box issue - YouTube

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Joffre richer-desroches. ... How To Install Replace Engine Coolant Thermostat and Housing 3.7L 2002 ...

Sounds like the heater core

There are two possibilities, one is the thermostat. Many people remove them which spoils the whole heating / cooling system. Since you changed the thermostat, I would check the heater valve on the heater which allows the hot water to circulate through the heating system.
It may be necessary to remove the heater box and flush the heater core since you talk about a lot of rust, which could have clogged the heater core and / or the pipes leading to the heater.

thermostat is sticking open

Hello! Thermostat should be a 190 degree...you may have an air blockage...Remove radiator cap start engine and leave cap of until all air bubbles are out (even after thermostat opens)...Cap and test for heat...if there isn't any heat...When that thermostat opens and hot water flows through the upper hose of the radiator that hose will be hot and hard..If you feel the heater hose only one will be hot which means that nice hot water is not passing through the heater core...That could be due to blockage or the control in the car isn't opening the valve on the core...check to see if the heat control is opening the valve...If it is, I would suggest that you purchase a back flushing kit ($10) A plastic tee fits into the inlet heater hose and a garden hose is then connected to the tee...Drain the radiator, remove the thermostat, and turn on the water...do this with heat control on high...The system will back flush out of the top of the radiator and hopefully clean the blockage...Reassemble ...Cap off the tee (cap is in kit)...Install thermostat (190) Is a better choice...Refill radiator...Start engine and leave the radiator cap off until all the air bubbles out............At that point you should have heat...Guru...Saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

replace termastat

The temp reading on the dash is a very big clue... Likely the thermostat (at the end of the large top radiator hose inside the metal housing) is stuck open. When that happens, the coolant in the engine never reaches full temp. Not only can that result in a low heat condition but it can also give you poor fuel mileage as the computer always thinks the engine is cold and therefore it adds extra fuel to keep it running.
Replace with a 195 degree(f) thermostat, run the engine (with the heater on full heat) to nearly normal temp, turn it off and wait about three minutes, then re-start and continue filling. Once full, add whatever is necessary to the recovery bottle and close it up and check for leaks.

1st you need to make sure no air in your system open you radaiator cap and your heater to max and see if air bubles or circulation is going on fill up accordingly otherwise you have blockage in your system or water pump if no circulation ////make sure no bubles all bubles should be gone////look for coolant circulation in your radiator make sure your thermostat is not defective or placed in the right position.

Make 100% sure before you go and spend more $$$ that (1) you have good coolant flow through the heater core; get engine to operating temp,then with heater fan on high and temp control on full hot carefully grasp heater in and out hoses(i use a in-fared heat gun to diagnose). They should be very close to same temp, if not, core is plugged or if equipped with a flow control valve, its not opening or there is an air lock in system.(2) If coolant flow is good, suspect the hot/cold blend door being stuck in cold position assuming you have good air flow. Its very rare for engine cooling to be ok and heater core coolant flow be bad , caused by a failed water pump! Hope this helps! Please rate me,Thanks!

How often has the coolant been changed? My only guess is that it hasn't and the hoses and the heater core are plugged up with goo and a flush is needed