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Heat Dilemma!!

1K views 17 replies 8 participants last post by  02TJeep 
#1 ·
Hi guys, I've been lurking these forums for about 6 months since I purchased an 02 TJ Sport. A lot of great info on here. I've done my share of searching but I still can't get the exact answers I'm looking for and hopefully someone here can shed some light on the issue I'm having. My current problem is that I have no heat coming from my vents. It blows lukewarm air at best on hot, and as a side note, my ac works fine. Once in a while when I turn the heat on it will blow nice and hot for all of about 5 seconds then it's back to lukewarm. With winter coming I need heat though!!!!! So far from reading posts on here I've tried all of the following. Replaced my water pump 2 weeks ago due to a leak (t he heat wasn't working prior to this repair either) ,changed my thermostat, flushed my heater core out 3 times on 3 separate occasions as well as using the prestone kit and flushing my entire cooling system out. I backlashed when I flushed the heater core too. I have also pulled the blend door actuator motor off and it is working fine. I manually turned my blend door and it is operating fine, I can feel it moving in both directions and hear it opening and closing. Both heater core hoses get piping hot as a side note. almost too hot to touch and barely any crud came out during the flushes I did. My blower motor also works fine. Can someone please help me and tell me what I am missing here or at least point me in the right direction. Thanks in advance for any help you guy can give me.
 
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#2 ·
Check down into the cowl vent. A lot of crap can get in there and block the air flow.
 
#6 ·
When you backflushed the heater core, how did you do it? Remove both heater hoses at front of engine? Force water through one hose? How was the flow on those hoses? Sent from my SAMSUNG-SM-G930A using Tapatalk
I removed both hoses at the front of the engine. Forced water through the inlet and then through the outlet. Repeated this process many times. The first flush i did i even poured vinegar into the core and let it sit for about 20 mins then flushed again. Did this type of flush on 3 seperate occasions. Water came out clear every time and the flow was great. The last time i did the flush i even installed a prestone fill and flush kit and cleaned my whole system out.
 
#8 ·
Its possible. The only reason im hesitant to think its packed up like that is because it was a garage kept jeep when i bought it. Cleanest engine bay I've ever seen in my life. It was woman owned and never saw any kind of abuse whatsoever. Worse comes to worse I'm gonna change the core but for some reason I done think it is the core.
 
#11 · (Edited)
If the hoses are hot then hot water is getting to the heater core...whether it's able to convert that heat in the core is still a question. The only other thing that could effect the heat is if a vent door is not closing or opening all the way and allowing cool air to mix with the hot air.
 
#14 ·
Yes you have checked the door, but have you checked the actuator when it is connected to the door? What does it do when the temp knob is turned?
 
#15 ·
Yea the actuator is working fine. I checked that first, then tried manually opening and shutting the door as well. everything seems to be working fine. I have ice cold ac on the cold setting and on hot nothing but lukewarm air. You can feel a change when you move the door and hear the door engaging and disengaging.
 
#18 ·
i think I'm starting to make some headway into diagnosing my problem. Yesterday my friend who is a mechanic had about an hour to spare so he took a look at my jeep. my lower blend door under the glove box is operating fine. The mevhanic started to play around with the other blend doors behind the radio somewhere and a little bit of heat started to come out. I'm guessing those doors may be the culprit? Does anyone know if there is an easy way to fix them? I also noticed that the vent on the passenger side seems to blow much hotter air than all the others. For now, he unplugged my ac compressor and for some reason that gives me a slight tinge of heat. I still don't fully understand what is going on but Id like to get some heat without spending 1000 bucks at the mechanics. Unfortunately the guy who looked at it for me yesterday is booked up for a while and I'm hoping somehow I can fix this myself.
 
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