Heater Core Revisited.

[JBDive]

Have you correlated these with the actual engine temperature readings? An inexpensive OBD bluetooth adapter would make this easier.

Either you've got an obstruction or a stuck thermostat. The dash gauge isn't specific enough for this. My money is on the heater core, though. :blah:

Good thought. I have one but generally looking at my phone to read it while driving isn't a good idea. I'll see if the app has logging built in. Considering I have a new, rebuilt engine and all new cooling system (radiator, water pump, therm, and some other crap) I should not be having any issues with the cooling system itself, outside of the heater core. Even replaced the clutch on the fan as I have the towing package so both mechanical and electric fan. Speaking of which man can I tell a difference with this replacement clutch. It is in full spin mode, loud as heck, for the first bit of driving.

 

[JBDive]

It keeps produce and rocks from blowing inside:happy175:

I am referring to the inside filter under the dash which if clogged will kill your recirculating air speed. Under the glove box.

 

[TomB985]

Good thought. I have one but generally looking at my phone to read it while driving isn't a good idea.

You look at your gauges, don't you? What's different about a phone screen displaying a reading and a gauge on the dash?

With all those new parts you're probably correct, I was just trying to suggest a cheap way to rule out an inexpensive thermostat that could cause a similar concern.

 

[tjkj2002]

My 02 is the same way. Very long time to warm
Up compared to the 03 with far less miles on it
I feel like it takes longer for the core to get “heat soaked” which is usually the time it takes to get to work

My '02 would be at operating temp in less than 2-3 miles even at 0 degrees,blowing good heat before the 1/2 miles if I started driving shortly after actually starting the engine.

At full operating temps the outlet temps in the center of the dash was 165-170 degrees on high fan speed,closer to 180 degrees on the lowest fan setting.

 

[Aceofspades]

Sounds like you had a perfectly working heater core. I have zero plans to replace mine but it does get hot - just not at the same time the engine is up to temp.

 

[JBDive]

You look at your gauges, don't you? What's different about a phone screen displaying a reading and a gauge on the dash?

With all those new parts you're probably correct, I was just trying to suggest a cheap way to rule out an inexpensive thermostat that could cause a similar concern.

Engine Coolant Temps
195 Degrees at highway speed, air temp low 40's to mid 30's
200 Degrees at city speeds, air temp low 40's to mid 30's

Heater Selection on Vent, full hot, low fan speed
Vent temps at highway, 125-130
Vent temps at city, 130
Vent temps parked, 135-140

New Observation:
Selecting Defrost or Defrost/floor the temps are FAR cooler, 90's maybe. Come back to vents, give it 5 mins or so and temps are back to 125-135. With fan speeds over second speed the temps drop to low 100's. Getting a lot of fresh air through heat selection which is noticed if I drive by smoke or a stinky car.

 

[GitEmSteveDave]

According to the service manual:

Ambient Air Temperature
15.5° C
(60° F)
21.1° C
(70° F)
26.6° C
(80° F)
32.2° C
(90° F)

Minimum Air Temperature at
Floor Outlet
52.2° C
(126° F)
56.1° C
(133° F)
59.4° C
(139° F)
62.2° C
(144° F)

 

[Aceofspades]

Somewhat and yes it needs cleaned. I had really horrible airflow when recirculating air was selected, I assumed a bad actuator. Pulled the glove box and in the upper right area you will see a "filter" or mesh and if you have never cleaned it out it will be pretty much clogged. Just stuff a shop vac hose in there to clean it out. I posted about this on another thread, let me see if I kept the image, nope, but here is the thread and the thread I referenced in finding the "filter".

http://www.jeepkj.com/forum/f202/c-heat-air-volume-vents-fix-64081/

Damn... all the time I spent messing around with both jeeps I never noticed that ...
Thanks - going outside now to look

 

[willowyric]

I'm in the same situation. Just had my core flushed, but still cool air when driving. Torque app shows my coolant temp between 195 and 197 while driving. As soon as i come to a stop the vents start blowing warmer air.
I actually just requested my local shop to replace the thermo and they instead flushed the core. They reported that the core seemed to have good flow, but didn't replace the thermo since the engine seemed to be heating up fine.
So to review; core was checked and has good flow. Vents blow hot when left to idle. Driving causes the vents to blow warm, or cool air.

 

[Joenavy85]

Vents blow hot when left to idle. Driving causes the vents to blow warm, or cool air.

Very odd, typically the problem I hear is that it's blowing cold while idle and warm to hot while driving, which indicates low coolant. I'd have to look at a proper system diagram to know for sure, but I'm going to guess that it's a thermostat problem.

 

[tjkj2002]

I'm in the same situation. Just had my core flushed, but still cool air when driving. Torque app shows my coolant temp between 195 and 197 while driving. As soon as i come to a stop the vents start blowing warmer air.
I actually just requested my local shop to replace the thermo and they instead flushed the core. They reported that the core seemed to have good flow, but didn't replace the thermo since the engine seemed to be heating up fine.
So to review; core was checked and has good flow. Vents blow hot when left to idle. Driving causes the vents to blow warm, or cool air.

Very odd, typically the problem I hear is that it's blowing cold while idle and warm to hot while driving, which indicates low coolant. I'd have to look at a proper system diagram to know for sure, but I'm going to guess that it's a thermostat problem.

Classic heater core restriction problem.

Look at the pic I posted of the heater core in a KJ.Fully plugged you will still have "good flow" through the hoses and core with both the inlet and outlet on the same side that can bypass the actual core itself.

 

[billp2000]

Same problem. Car operates well but with no heat; heat indicator on dash indicates proper heating/cooling. After multiple flushes (back and forth) soaked heater core in CLR for three days then flushed. Water flows freely and clear both directions. Both hoses hot when car reaches correct temperature. Water flows clear when hoses disconnected. 2002 Liberty Limited. If the heater core is completely clogged will water still flow through?

 

[ltd02]

Same problem. Car operates well but with no heat; heat indicator on dash indicates proper heating/cooling. After multiple flushes (back and forth) soaked heater core in CLR for three days then flushed. Water flows freely and clear both directions. Both hoses hot when car reaches correct temperature. Water flows clear when hoses disconnected. 2002 Liberty Limited. If the heater core is completely clogged will water still flow through?

Are you sure your blend door is working?

Pretty sure water will flow freely even if the core is plugged. It will just bypass to the outlet and not reach the plugged heat exchanger portion.

 

[uss2defiant]

Classic heater core restriction problem.

Look at the pic I posted of the heater core in a KJ.Fully plugged you will still have "good flow" through the hoses and core with both the inlet and outlet on the same side that can bypass the actual core itself.

did you read tjkj's post?