Mclerran11

It gets a little cold here in Utah. Not Nebraska cold or Canada cold, but chilly. As such, I have need to run my heater from time to time. I noticed that it was only blowing moderately warm air, despite the engine being fully warmed up, so I replaced the thermostat. Now the heater blows nice warm air, but only through the PASSENGER vents. The two driver's side vents still blow cooler air. If I didn't know better I would say I have dual climate controls with no way to switch them!!

The fan still blows powerfully, so I know it's not a blockage issue, but the heat only seems to be going to the right two vents...

Anyone else run into this? I don't know the anatomy of the ventilation system, so I don't know if it's even possible to diagnose this properly, but any help would be FANTASTIC!

Tree Frog

Well sir, to start with read this thread all the way through and then go from there.
https://www.jk-forum.com/forums/stoc...system-293916/

On the 3.8's like yours it may very well be a casting sand issue. On the 3.6's I am now being told it is a sludge formed from the anti leak put into the coolant at the factory.

It seems both will plug up the heater core. Somehow the way the heater core is set up the coolant has like a low pressure zone on the drivers side and this allows a build up to occur weather it be casting sand or sludge. Must be the way they are ducted that the fan blows through the coil separately driver to passenger. It always seems like its the drivers side that has weak or no heat.

So start with a serious back flush. Flush it till it runs clean. You really want to get as much of the heater core flushed out as you can.
Refill it and try the heat again.

Like I stated in the other thread, you do not even want to see what it takes to change the heater core. I am still in shock from some photos I found of the repair process to change out a heater core.
I would love to hear from someone who has done it and have them tell us just how hard it really is.

Good luck and let us know what you find, what repair process you use.

Oh and WELCOME to JK Forum!

LidLess07X

What year is your JK ?

The sand in the cooling system issue started with the 3.6 Pentastar in the 2012 but most of them don't get any heat at all.

If you are getting good heat in some areas but nothing in others I would say it's it most likely a blend-door issue though I have experience with this.

Are you getting air flow that just isn't hot in those areas ?

101gargoyles

Agreed
Little or no heat problems end at the heater core where the fluid returns to the engine. The fluid does not travel from side to side or upper or lower vents. Only the air blown through the heater core does that Blender door or selector cable problem is likely but could also be a partially disconnected left side area air duct. Hard problem to track down up behind the dash

He's driving an '08

Mclerran11

I read through that entire thread and I have the exact symptoms they describe. My overflow has about 2" of dark sediment in it. If this is only a pentastar engine issue is my sediment and symptoms potentially coincidental?

Mclerran11

"Blender door?" I have no idea what that means... Is that a part? #forgivemyignorance

JKZinger

It is not the blender door. You have the casting sand issue which they fixed on mine for good a couple years ago by replacing the heater core. I had cold air coming out of the 2 left side vents and hot air on the right side. The system won't even allow you to blend air to the right or left side, just up or down from the vents to the footwell vents.

Tree Frog

I do not believe the blend door has anything to do with this problem. Especially with a sludge in the coolant reservoir bottle.

First thing I would do is to pullout a sample of this sludge from the reservoir. I used a fluid transfer pump with a long hose and pumped it into a clean plastic water bottle.
Casting sand will be a kind of fine grain sand like material. The stop leak stuff looked kind of like mud with no gritty feel to it at all.


Here is the Star bulletin for those that missed it. I had a heck of a time finding this.
Not sure what years this applies to.

Case Number: S1207000008
Release Date: 12/12/2012
Symptom/Vehicle Issue: Poor Heater System Performance
Note: Sludge may build up and restrict coolant flow in the heater core. The heater core may still be restricted even if sludge is not visible in the overflow bottle.
Diagnosis:
1. Remove radiator cap and inspect coolant overflow bottle for buildup of sludge on. See (FIG1) and(FIG2)
2. Is sludge found in the coolant overflow bottle?
a. Yes >>> Proceed to repair procedure.
b. No >>> Proceed to step 3.
3. Re install the radiator cap and run the engine until operating temperature is reached.
4. Operate the HVAC in full heat panel setting and inspect that heat is produced on both sides of the vehicle .
5. Is heat produced on both sides of the vehicle?
a. Yes >>> This Star Case does not apply.
b. No >>> Proceed to repair procedure.
Repair Procedure: If Sludge is found in the radiator overflow bottle or poor heat is produced by the HVAC system the following repair procedure should be followed
.
1. Flush cooling system with Mopar Cooling System Flush
Note: Repeat flushing until the system produces clear water.
2. Replace the following components
• Radiator
• Heater core
• Radiator cap
• Engine Oil Cooler
3. Refill the cooling system with the appropriate coolant and perform verification.

101gargoyles

Go nuts guys
If you can't figure out the difference between the heated coolant side of the HVAC system that might have sand in it...that couldn't possibly exist from building the engine FROM the air duct side of the system that directs heated AIR from one area to another using the selector knob to actuate gates that open and close then I'm wearing out my fingers here for nothing. The selector chooses between defrost/floor heat/dash vents. Difference in amount of heat from one side or another in the basic heating /cooling system would require a 5 pound bag of sand in an AIR duct.
If there was sand in your liquid coolant system your water pump would become toast and your engine would be toasted long before you knew you had no heat on the left side of your dash.
That said I'm outta here....Could also be a Gubment conspiracy I guess. Hope you you all find enough sand to build a beach

101gargoyles

OK
Before you freak out because of the supposed sand issue.
-Sneak into the kitchen drawer that has your wife's turkey baster in it. You know the one that has the rubber bulb on top that you squeeze to suck up the juice from the pan.
-Put it under your shirt and as you're whistling, head out toward your overflow tank.
-Use a piece of hose to extend it to reach the bottom of the tank for a sample.
-Deposit the sample on the piece of paper towel you wrapped the baster in to help you get it out of the kitchen
-When you see that the deposit on the paper is normal harmless coolant sediment post a picture for the sand people to see.
-Throw out the baster and say the dog ate it-you don't want your next turkey to taste like anti freeze.