Novak Conversions Jeep Wrangler JK shifters

Heat not working properly

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msgntsu

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New to group... I have a 16 JKU. At the end of last winter, I started noticing that my jeep was not warming up as hot as the previous year. This year, it just not starting to get cool enough that I need some heat, but I an still noticing that the heat is not hot enough. Some quick snapshots of data is below.

1. Ambient air outside is around 40 - 50
2. When I first start the jeep, I watch the coolant temp rise. Once it gets to about 188, it drops (I'm assuming that the thermostat opens) back to about 170.
3. As the temp rises again, it eventually goes back to about 188 and rarely any higher (at least when it's this temp outside). last week, it was in the 60's and I did see it go up to around 200
4. The other thing I notice is that I have to keep the temp knob all the way down. If I back it off any, the temp of the air coming through the vent, or floor gets much cooler. Even if I just back it off slightly say 1 or 2 notices (basically it's 80-90% all the way).
5. In case it matters, this is over a 30 minute drive to work (mostly highway driving).

Thx. in advance for the help.
 
Do you have a CEL on? If your coolant temp is staying that low, you should. Your thermostat is probably stuck open. If it's stuck closed, the heater will blow cold air while the car over heats. If it's stuck open, the engine will run abnormally cool.
 
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Same as @Dirty Dog I suspect the thermostat is stuck open. Had the same issues on my wife’s JKU. Eventually the CEL came on with the code, just can’t remember the code. Had it fixed and all has been solved.
 
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Thx. for the quick reply. I should have added that I CEL is not on . Also, I didn't suspect it was stuck open because it seems to heat properly in the summer. I guess it works more accurate because it's hot outside, so being stuck open is a bigger problem in the winter?
 
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msgntsu said:
Thx. for the quick reply. I should have added that I CEL is not on . Also, I didn't suspect it was stuck open because it seems to heat properly in the summer. I guess it works more accurate because it's hot outside, so being stuck open is a bigger problem in the winter?
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It will (or should) throw a P0128 code. It's possible that it's not totally stuck, and works properly sometimes. If I recall correctly, this code only throws if the condition occurs on multiple sequential startups. Thermostats are cheap, and since it's the most likely cause, that would be my first step.
 
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Yes it takes a while for the code to appear from my understanding. if there is an error in the system, but then the next few times it does not receive the error message (it gets hot enough) the computer resets itself. I suspect it is because of the summer it the engine was getting warm enough. My wife‘s came on in the fall when the doors where off and she was running the heater full blast nonstop. Then it the code would ago away a few days later. Using the heater full blast was enough I guess to cool down the engine temp and kick on the code.
 
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msgntsu said:
Thx. again. I will replace it and see how it goes. I'm surprised I haven't gotten the CEL since this happens every single day and has been for a very long time.
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Best I can tell it seems like the temp needs to hit 185 for a few consecutive times in order to throw the code. It seemed like if it stayed 188 or higher it wouldn’t throw the code.
 
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If replacing the thermostat doesn't fix it, my next guess would be that there is air in the system. Easy for this to happen if you allow the coolant to get a bit low. Ensure that when you replace the thermostat that you are getting hot air in the cab before thinking you are done. Getting the air bubble out of the heater core on these engines is a bother.
 
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Hello, I thought I sent a reply, but I don't see it. Should I stick with a MOPAR thermostat, or is an aftermarket part acceptable?

Thx. again.
 
Sorry for the additional questions. I was watching a video to confirm how to perform the replacement. I noticed that I need to drain the radiator. A few questions:

1. How much fluid will I lose out of radiator and hose assy?
2. Assuming I shouldn't reuse the current fluid? I changed it about 40K miles ago
3. I am also having trouble purchasing the MOPAR coolant. I did find a dealership that has some, but was wondering if I need to MOPAR coolant, or can I usse aftermarket. If so, can I mix with what's in the jeep currently, or would I need to totally replace? Also, if so, is there a recommendation on a different brand?

Thx again.
 
msgntsu said:
Sorry for the additional questions.
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I think most people here like questions. Feeling good when you help someone is pretty much hardwired into most people. There have been any number of studies (with good methodology - I tend to ignore sloppy science) showing that helping others reduces stress, bolsters self-esteem, and makes people happier. If more people realized this, maybe there wouldn't be so many Karens in the world.
msgntsu said:
I was watching a video to confirm how to perform the replacement. I noticed that I need to drain the radiator.
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Meh... it's not really a "need"... you can certainly change it without draining the radiator first. But it'll get messy when you take the hose off.
msgntsu said:
1. How much fluid will I lose out of radiator and hose assy?
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Depends. To avoid a mess, the coolant level just needs to be lower than the thermostat housing. But it's sort of difficult to know the exact level, unless you have X-Ray eyes. So the answer is probably "all of it".
msgntsu said:
2. Assuming I shouldn't reuse the current fluid? I changed it about 40K miles ago
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You can, provided you use a really clean container to catch it, and use some sort of filter when you put it back. Fluids are pretty cheap though, so I probably would not, if I had any other option.
msgntsu said:
3. I am also having trouble purchasing the MOPAR coolant.
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Here you go. Amazon is your friend...
msgntsu said:
I did find a dealership that has some, but was wondering if I need to MOPAR coolant, or can I usse aftermarket. If so, can I mix with what's in the jeep currently, or would I need to totally replace? Also, if so, is there a recommendation on a different brand?
Click to expand...
As long as you're using an OAT coolant from a reputable manufacturer, you're fine. Just read the labels.
 
msgntsu said:
Sorry for the additional questions. I was watching a video to confirm how to perform the replacement. I noticed that I need to drain the radiator. A few questions:

1. How much fluid will I lose out of radiator and hose assy?
2. Assuming I shouldn't reuse the current fluid? I changed it about 40K miles ago
3. I am also having trouble purchasing the MOPAR coolant. I did find a dealership that has some, but was wondering if I need to MOPAR coolant, or can I usse aftermarket. If so, can I mix with what's in the jeep currently, or would I need to totally replace? Also, if so, is there a recommendation on a different brand?

Thx again.
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For electronic components like sensors the general idea is to use Mopar because for some reason the computer in the vehicle doesn't like aftermarket.
However, when you get to mechanical devices like a thermostat it doesn't matter. I know the guys at the local Oriellie's and while I know a great deal more about my jeep, they see what brands come back and complained about so I go with there suggestion.. which is usually just the cheapest for simple parts.

For coolant, I don't think brand matters that much. Perhaps we should send the suggestion to Project Farm to test if it matters at all. (Yes, the type of coolant matters OAT, etc.)

You can totally mix other coolant brands, the "type" is a automotive standard with each companies own minor spin on it.. maybe.. or they are all exactly the same thing.
 
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Hello I have a heat issue on s 2011 with 3.8l. Last year I flushed heater core and got heat again. But now it just blows completely cold. Things I've noticed is the hvac controls sometimes flash on defroster button and takes awhile to kick on, secondly the temp gauge shows normal temp before any of the hoses get hot. So far I have flushed whole system again and it was not very dirty. I replaced thermostat, changed coolant. Theblend door works properly and air comes out decently strong. Both heater core hoses get hot. Im starting to wonder if that temp sensor is bad, but will that cause heat not to work? I know some vehicles have heater control valves but idk if wranglers do. I need to figure this out, its been in the teens this week
 
Tbelgarde86 said:
Hello I have a heat issue on s 2011 with 3.8l. Last year I flushed heater core and got heat again. But now it just blows completely cold. Things I've noticed is the hvac controls sometimes flash on defroster button and takes awhile to kick on, secondly the temp gauge shows normal temp before any of the hoses get hot. So far I have flushed whole system again and it was not very dirty. I replaced thermostat, changed coolant. Theblend door works properly and air comes out decently strong. Both heater core hoses get hot. Im starting to wonder if that temp sensor is bad, but will that cause heat not to work? I know some vehicles have heater control valves but idk if wranglers do. I need to figure this out, its been in the teens this week
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Are you sure all the air is bled out of the system?
 
In order to properly bleed the system you need to raise the front of the Jeep up 6-8" and then take the radiator cap off. Then start the Jeep and let it idle and add coolant as the level drops.
 
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