T-stat or something else.

[CzarKJ]

Well just yesterday I started having an issue. When in traffic or at a stop light my heat blows cold. When moving its hot. On the highway I could cook a chicken from the vents. No issues with overheating. Blower works on all speeds. Temp gauge just below halfway as it always has been. All winter never had an issue. After doing some searching I am thinking either t-stat is sticking and takes some good flow to work or the mystical air bubble. I don't think its the heater core since it gets so hot. Coolant last flushed and changed by the dealer about a month or two ago. Anything I am missing? Heading in the right direction?

Things I am going to check in an hour or two when it cools down.
Coolant Level (and color)
How quickly the Jeep heats up
E-fan (unlikely but might as well)

 

[olmsb4d2]

I had the same problem and it was low on coolant. I added some and it was fine but all of the sudden tonight it overheated. It seems like the two problems should be related but at this point I'm drawing a blank...any ideas

 

[tjkj2002]

Low coolant which means a leak.Find the leak and fix.


Stuck closed t-stat would just plain overheat,partially stuck open or stuck open t-stat will just take forever to get to operating temps and set a code(P0128 in most cases).

 

[02blue]

Well just yesterday I started having an issue. When in traffic or at a stop light my heat blows cold. When moving its hot. On the highway I could cook a chicken from the vents. No issues with overheating. Blower works on all speeds. Temp gauge just below halfway as it always has been. All winter never had an issue. After doing some searching I am thinking either t-stat is sticking and takes some good flow to work or the mystical air bubble. I don't think its the heater core since it gets so hot. Coolant last flushed and changed by the dealer about a month or two ago. Anything I am missing? Heading in the right direction?

Things I am going to check in an hour or two when it cools down.
Coolant Level (and color)
How quickly the Jeep heats up
E-fan (unlikely but might as well)

How did this work out? Any solution.

 

[CzarKJ]

How did this work out? Any solution.

Found a pinhole in the side of my radiator. Replaced it and all was right.

 

[02blue]

Glad to hear! Must have missed your original post. Been a very busy April. I've had a few similar issues/symptoms.

I had one rad fail shortly after a flush too. I saw the leak (usual spot). Now have a Mopar replacement and all seems well. First four years I had my KJ, the cooling system was rock solid. Last three years it's been one little thing after another, fan relay first caused HG to fail, then two radiators (one cheapy), two rad caps (one was defective from the start), one hose. Think I've got it beat this time. Of course it's all new now. I had the weak heat from Rad issues and rad caps. Great on the highway but cool in traffic I guess because of the lack of pressure and a small loss of volume. Now all is good.

 

[centermass556]

Some Cooling systems problems can't be found until the Engine is cranked and "under pressure". Seep Leaks from around the water pump gasket are killers. A lot time folks will think it is just drops from the A/C in the summer. A "sometimes" thermostat ***** to hunt down too. When some days it works, then the next day it won't open for anything. Squeezing your Rad hoses while the engine is running will help too.

After I gave my Wrangler to my daughter thats in college, I picked up an A to B beater. in the form of an explorer...The cooling system issues with that thing were a beast. I got to the point where I thought Ford should make an Alaskan Series Explorer/Truck. It would have a heated tailgate...So you can keep your hands warm pushing it in the winter.