2016 Wrangler blowing less warm air on drivers side

T

Tom5170

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Jul 20, 2026
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MI
The heat coming out of the front vents, passenger and both middle front seem to blow hot. The driver front vent left of steering wheel has a reasonable temperature difference compared to the middle and passenger vents compared to the others. When I put it on defrost, the driver side defrost vent at the windshield blows cooler than the passenger defrost vent. If I raise rpms, the driver defrost vent and the driver window defrost vent get hot. So yeah - Seems like there’s a temp difference on the driver defrost vent and driver window defrost vent compared to the others.

I just bought this jeep a few weeks ago. Back in January 2026 at 153k miles, the dealership I bought it from did a “cooling system flush” from previous owner. It has 158k miles.

Should I attempt to flush the heater core? Does this sound like what it is? I thought 2016 was safe from the casting dust lol
 
Sounds like there's still an air bubble in the system. Worse would be blockage at the heater core but I'd try and burp the system 1st. It's free to do.
 
Yeah I think I’ll do that. Should I just run it with the rad cap off and use the screw on the t stat housing? First time owning a wrangler lol
 
Get the front end 6" higher than the rear, take the cap of the rad, start the Jeep and let er warm up. Keep an eye out for bubbles.
 
pc1p said:
Common issue... this seems to have fixed my issue (can't tell for sure until winter comes): https://wranglerjkforum.net/threads...-2010-islander-side-project.32367/post-472039
Click to expand...

I went and got some 5/8” 10 foot vinyl hose at Menards and some 5/8” couplings and cut the hoses in half and got a garden hose and a bucket. I spent probably 2 hours flushing back and forth… “agitating” with the water flow and blowing through the hoses with my mouth in both directions. Then I plugged the bottom Hc hose w a 5/8 bolt and got a funnel and filled the heater core as best I could with distilled water and then removed the bolt plug and blew all the water out with my mouth on the hose. I did this a bunch of times to get the tap water out and then I refilled with coolant and bled the sh*t out of it. Now the heat is definitely better on the drivers side. Some grains came out light brown colored. It took a long time flushing until I didn’t see anything else. Maybe a tablespoon full of debris.
 
pc1p said:
Nice! In total I got ~1/8” cup of debris between the days and days of flushing and rinses…
Click to expand...

Damn. I had an s10 that had crappy heat suddenly and I flushed out black chunks and had toasty heat afterwards lol. I may try to flush the heater core on the jeep again before winter hits.
 
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Tom5170 said:
Damn. I had an s10 that had crappy heat suddenly and I flushed out black chunks and had toasty heat afterwards lol. I may try to flush the heater core on the jeep again before winter hits.
Click to expand...

If you follow that link to where I did mine, I think that hose adapter makes a big difference... I got the majority of my "chunks" out with that.
 
pc1p said:
If you follow that link to where I did mine, I think that hose adapter makes a big difference... I got the majority of my "chunks" out with that.
Click to expand...

Interesting write up! Looks like a tool I should buy (even if I don’t need it….I love tools!)

My heater in my 2016 will cook me out. I wonder how prevalent the clogging of the heater core is. I’m guessing sediment falls to the bottom of the heater core and basically can’t get back out.
 
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