Heat blows hot on passenger's side but cold on driver's side

[William]

Hello I am new here sorry if this is the wrong place and thank you for this forum. I have a 2010 jeep wrangler Sport. 3.8 with 211000 miles. I am having a continuing problem with my heat. It blows hot as hell on the passenger side and cold on the driver. I know this is a common problem and I have replaced the heater core twice two years in a row. Both times it fixed the problem this time there are no leaks no smell and no film on the windows. I went through all last winter with the problem and hope to.not do so this year as I drive for work all day every day in it. This morning I took the outer part of the door blend gear off and as far as I can see they all move freely by hand and the air changes as it should think
Fluid is good and no sludge in the reservoir. I am curious are both heater hoses supposed to be hot? One is not hotter or cooler than the other. I'm considering just back flushing the heater core and see what happens but I can not tell which is inlet and which is outlet. Under the dash the tubes are both the same and the hoses coming out through the firewall are the same. Any one have any suggestions . Thanks for reading this.

 

[Chris]

Both heater core hoses should be hot. One flows coolant in, the other flows it out, so basically it's circulating, just like the radiator.

So they are both warm / hot then? It almost sounds more like a blend door issue to me.

 

[LCBOYER]

About how much different is temperature?

 

[Jeepguy1]

this isn’t a heater core, or a flow problem. It’s in the air box somewhere.
If you are getting hot air on one side of the cabin with lots of air flow, and cold air on the other side, with an equal amount of air flow, then you have an issue where the blend door, or a flow door isn’t positioned correctly.
Let me guess... this started happening after a recent repair in that area ??

Do you have dual climate zone option in that vehicle ?

 

[Meatwood Flac]

this isn’t a heater core, or a flow problem. It’s in the air box somewhere.
If you are getting hot air on one side of the cabin with lots of air flow, and cold air on the other side, with an equal amount of air flow, then you have an issue where the blend door, or a flow door isn’t positioned correctly.
Let me guess... this started happening after a recent repair in that area ??

Do you have dual climate zone option in that vehicle ?

I’m having a similar issue. 2011 jk sport. I’ve just recently (as of 2 hours before posting this) had a coolant flush, dye test and Coolant refilled, new thermostat and Thermostat gasket with a new radiator cap. Water pump is about 8 months old and working fine.
My problem is that, depending on the day, My driver side vent and floor vent can be anywhere from 10 - 30 degrees cooler than my passenger side when turned to heat. In the winter time this equates to basically no heat on the driver side. The left middle vent is lukewarm and the farthest vent on the driver side is always colder than it.
I’ve checked the blend door actuator for proper function and it moves perfectly.
My heater core hoses are both hot to the touch in the engine bay before running into the firewall, and the metal pipes that run in and out of the heater core are only about 5 degrees different, ranging around 135 degrees (checked with an IR thermometer from behind the glove compartment).
There has never been a coolant smell and I can see no signs of a heater core leak.
What else could this issue possibly be? I have been told by a separate mechanics shop last winter that the heater core needed replaced, but in lieu of all the evidence I’m beginning to think that they have suggested this simply because they can’t figure out another possible issue.
ive run out of ideas and have searched countless forums.
My engine doesn’t overheat as of now, and If it is the heater core I’d rather buy a snow suit than pay to replace it since the only symptom I’m experiencing right now is poor heat on one side.
AC blows the same temp in all vents when on full Blast if that is relevant. Send help.

 

[Anybodyhome]

I'd say it's the blend door actuator as this sounds similar to an issue I had a couple years ago. It's a warranty fix if you're still in the window, but about $170-250 out of warranty, if I remember correctly.

 

[Meatwood Flac]

I was sold on that idea as well until I got under the steering wheel and physically saw it move perfectly from end to end when I changed from heat the cold.

 

[KrazyChinaman]

I had the same issue with my jeep! I have a 2013 Jeep Wrangler Rubicon 10th anniversary edition. It’s not the blend door actuator! It’s the heater core. Disconnect the radiator hose that runs through the fire wall. The top and bottom hoses. Grab your garden hose and attach it to with one of the two hoses and turn on the water full blast. Do this in both directions a few times! I personally think it’s because 2 different types of antifreeze were used. It causes these boogers to clog up the fins in your heater core and it does not give off heat. This is extremely bad for your motor. There is no sure fix to this issue and if you ask Jeep they’ll say “what issue?” I have had to blow out my heater core a few times now. Approx twice a year!

 

[MacGuyver]

This is a classic jeep heater core issue. Driver side cold, passenger side hot. Do a heater core flush. There are tons of vids on it all over the internets.

The hard part is getting the air out when you connect everything back up. Do the work with the front end higher than the back. As much difference as you can. The vids should cover this as well. It can be a bit of a pain to get all the air out.

 

[JKTimmah]

Yep, heater core. I'm dealing with it right now. I'm a bit torn though. I did something I never do..... bought a warranty on the Jeep when I got it. I bought it due to the oil cooler problem these tend to have. I really didn't want to tackle that one myself. I'm torn because I don't know if I should replace the heater core myself, the 'quick' way, or let the dealer replace it the 'by the book' way. I just don't like the idea of a 'mechanic' tearing my dash apart, lol.

T

 

[MacGuyver]

Just flush it with a garden hose. Both directions for a few minutes. Unless it is leaking there is no reason to replace it.

edit: I just re-read your OP and I'm curious that you have had to replace the core twice in the last few years. This is not normal and there is something else going on.

A couple things.

1. Do a flush of the core but make sure you catch what comes out, checking for sand. Chrysler does have the occasional engine that comes out of the factory with casting sand still in some of the ports, though I would think you would have had bigger problems long before 211K .

2. What coolant are you using? What coolant is the dealer using or whoever replaced the last couple heater cores? The old stuff and the new stuff mixed make jelly. I only ever put universal in my engine to avoid this issue. My mech does the same thing.​

3.When is the last time there was a complete super flush of the entire coolant system? Small particles that will pass right through the primary radiator can block-up the heater core. Chrisfix has a how to on this on youtube. At that mileage, who knows what is dancing around in the system​

 

[Reme Allen]

this isn’t a heater core, or a flow problem. It’s in the air box somewhere.
If you are getting hot air on one side of the cabin with lots of air flow, and cold air on the other side, with an equal amount of air flow, then you have an issue where the blend door, or a flow door isn’t positioned correctly.
Let me guess... this started happening after a recent repair in that area ??

Do you have dual climate zone option in that vehicle ?

U

Question, I'm having this same issue and it did happen after an air bag warranty issue. Should I contact the dealership and tell them. I know I'm not going to pay an arm and a leg for something that they may have caused. Could you give me more detail on your comment?

 

[SouthernSass]

Ok, I'm having a similar issue, 2011 JK w/ 140k+ miles. A couple years ago my left driver side vent started slowly blowing colder while the heater was on, now it's progressed to the left center airvent. The vents also don't blow quite as hard, but not a supre noticeable amount. I've also noticed that switching between vents takes a few seconds. I can hear it thinking and kinda clicking a litte. Nothing when I turn the engine on and off though. I also don't leave my AC/Heat on when I turn my Jeep off. I found several websites that claim its the blender actuator on the driver's side, but now I'm seeing this. Sooooo, is this a heater flush, a blender actuator, or something else? I've looked at so much my brain feels like mush!

 

[Anybodyhome]

Ok, I'm having a similar issue, 2011 JK w/ 140k+ miles. A couple years ago my left driver side vent started slowly blowing colder while the heater was on, now it's progressed to the left center airvent. The vents also don't blow quite as hard, but not a supre noticeable amount. I've also noticed that switching between vents takes a few seconds. I can hear it thinking and kinda clicking a litte. Nothing when I turn the engine on and off though. I also don't leave my AC/Heat on when I turn my Jeep off. I found several websites that claim its the blender actuator on the driver's side, but now I'm seeing this. Sooooo, is this a heater flush, a blender actuator, or something else? I've looked at so much my brain feels like mush!

Probably your blend door actuator.

 

[SouthernSass]

Probably your blend door actuator.

Thank you, Anybodyhome! That's what I had found and was getting ready to purchase the part to replace it when I found this thread where further up they mention that it could be that I need to flush my heater core. Trying to knock it out the first time. ​

 

[Anybodyhome]

Thank you, Anybodyhome! That's what I had found and was getting ready to purchase the part to replace it when I found this thread where further up they mention that it could be that I need to flush my heater core. Trying to knock it out the first time. ​

There are a couple YouTube vidz you can check out if you're going to DIY the replacement.

 

[DwayneG]

I still can not understand why the heater core would allow it to get hot on the passenger side but not the driver! Can someone explain that to me? I am not saying your wrong but it don't make sense to me.