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While the A/C is on, The Jeep randomly blows HOT air from the floor vents for 3-5 mins then stops

WranglerMan

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I’m here in Houston and need recirc as there is just to much smog so this needs to be addresssd by FCA
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Jeepsterfreak

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Has anyone determined if the hot air is flowing past the heater core or does it seem to be air from outside at ambient temperature?

What a strange phenomenon. Why couldn’t Jeep just design the system to open the recirculation gate periodically if they were worried about O2 rather than pump uncooled air to the heater vents?

If what FCA claims is true, then wouldn’t the same thing happen in the winter? You would get a blast of cold air unless it is flowing past the heater core first.
 
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JimL

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My Rubicon has done this a couple times. Various manufacturers use the "dry out" function to prevent odor build up in the HVAC system. In the old days, we used to instruct customers to run the A/C on "foot" mode for a few minutes to keep from blowing stinky air in the passengers faces.

A/C evaporator cores have a tough job, living wet and recirculating "human animal" air. There are certain kinds of mold that love to live on the aluminum core. Various coatings have been tried for many years.....it always gets back to the same long term problems.

There is no perfect answer to the long term problem. Time will tell if this keeps our A/C systems smelling OK better than the old methods did!

Thanks for telling us about the operation. I do notice that it mostly occurs when I don't shut off the ESS system, but once it did it at cruise for about 2 miles. Sure would be good for Jeep to put out more technical info for owners....like what to expect with system operations.

JimL
 

Tototrvlr

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Have a brand new JLUR. Doing the same thing. Randomly blowing warm/humid at the feet on passenger side. A/C is set to dash vents only. Recirculation is OFF. Warm air only lasts a couple of minutes. Dash vents keep blowing cool air.
Took it to the Dealer yesterday. Dealer turned it into Jeep and received this response: "You can perform a system calibration of the HVAC door actuators if you like but no DTCs correct? Normally with the recirculation door on too long the vehicle calls for fresh air to be brought in for a short amount of time and during that event a Ram Air effect will allow the passenger side to only feel that event." Ok, but I told the dealer we experience the event when the recirculation is off. The system is already bringing in outside air.
 

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My wife said the same guy who designed the A/C to work like this was probably the one to have auto stop/start set to on :mad:
Yep, kiddie engineers... Still wet behind the ears... They think that they need to add all the whiz-bang newest ideas so that they can put it on their resumes and they will look better for their future employers. They are quite willing to make things that are unreliable and you need to take to a dealer to get worked on. I suspect that many of them have never even changed their own tires and rely on the roadside assistance provided by their car's manufacturer or AAA.
 
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NavyVet1959

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I’m here in Houston and need recirc as there is just to much smog so this needs to be addresssd by FCA
I don't think we really have smog here. What you are probably smelling is just the exhaust from other vehicles, but that is not exactly smog, but it does contribute to *making* smog.

What we really need recirc for in this area is to cool the vehicle to an acceptable temperature. If you are only cooling the outside air, you're going to get whatever temperature difference (T) that the air-conditioning system might be able to get and the best inside temperature is going to be the outside temperature - T. Let's say that it is 100F and you have a 20F T. The best you are going to achieve is 80F if you are just using outside air. If you are on recirc, then you are cooling the already cooled air and it will keep going down until the limits of the cooling system or you reach a balance between the BTUs that the air-conditioner can remove from your vehicle and the BTUs that are input into your vehicle by the sun or other radiant (or conductive) heat sources (hot road, engine compartment, etc).
 

xeon

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Here is my experience at the dealer and some info straight from FCA via the dealer.

I have the problem you are all describing. It will be blowing nice cold air and then POOF a blast of hot humid air will blow in on the floor for a very brief moment. While at dealer I mentioned it and they said there is an A/C software update but they don't know what the update exactly does, they just know there is an update. So they do the update and within the hour FCA is on the phone with the servivce manager because he saw my complaint and software update hit their system. He asked him what am I experiencing so the service manager told him and the FCA rep said the following...
"Owners are experiencing lack of cooling or bursts of hot humid air. Check the lower left corner of the condenser for leaks if A/C is not blowing cold enough (they have some leaking units). For the bursts of hot air explain to the customer that if you are driving for long periods of time with the recirc button on the computer will open the damper and allow a burst of outside fresh air in so that oxygen levels will not get low" NO I'm not making this up!
He also said that this occurs while it is on MAX A/C only but I told that service manager that's not true.

The service manager was kind of chuckling and says that this falls under "normal" because the Jeep was designed that way. I told him I have tried to replicate it by opening the recirc damper and can't get the same effect which leads me to believe there may be another port which allows this air in. When I simply hit the recirc button to go to fresh air the A/C easily handles the humid air from outside and chills it. If there is some other damper we don't know about that allows straight up hot air in directly from the outside that would explain it.
So... it is normal BUT maybe this software will do something. The longer you drive the more likely it will happen because the computer reads the recirc closed longer. I'll see if it resolves the issue and post back.

My wife said the same guy who designed the A/C to work like this was probably the one to have auto stop/start set to on :mad:

@ JeepCares you are correct that people need to report this. This is on FCA's radar and they are aware of the issue. The more reports the more likely to keep progress on it.

https://www.jlwranglerforums.com/forum/members/13530/
I am not sure about anyone else but this burst of hot air happens for me without the recirculation activated and without max AC. With kids in the car... it can be 80F outside and they want the inside to be 69. So we have the climate control set to that. Otherwise I never use the AC. Windows work good. Oddly on long trips in the morning when its cool below 60... I might not have the windows down nor have the AC on and those same bursts of hot air come in. Anyone else having the same issues?
 

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So another piece of the puzzle... people are getting this same effect with the recirc OFF. I keep mine on and was told by the FCA via the service manager that it occurs on MAX A/C with recirc ON. So we have debunked both of those.

Correct me if I am wrong but the heater core should not be hot when the temp is set to cold. A heater core generates heat by allowing hot coolant to flow through it. If hot coolant were flowing through it, even if the blower wasn't on, the cabin would receive that warmth.
The reason I say this is one post asked is it bursting air over the heater core. I don't believe that is the case. The air I am feeling and actually smelling is hot damp air from the outside. Again, I can't replicate it using the recirc button set to open which leads me to believe there has got to be another damper door.

I know what the other guy is saying about the mold and evap coils, etc... but I don't think that is what is going on. Old school mechanics will tell you to put your temp on hot and run A/C on max to dry the ducts and evap coil off to get rid of the wet sock/wet dog smell.
There is no way they are trying to achieve that by bringing in hot humid air from outside. And yes, this begs the question will the opposite be true in winter. Next time I'm under the Jeep I plan on poking around for a possible extra damper flap.
 

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I have noticed this as well but for me it seems to be with the dual climate control. When I am alone in the Jeep I have them synced. When my GF is with me she likes to have much warmer air blowing on her. I noticed that at some point I am feeling warm air from the floor vents as well even with driver side set to LO where as hers may be set to 74.

I have gone to the climate control app and then sync the dual thermostat. After this is seems to reset the system and I am able to get cold air again while hers can be warmer.
 

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My guess is that it's a coincidence. Try driving for a decent amount of time with it on sync and I think you will see it occur. I keep it sync'd pretty much all the time and it happens.
 

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Correct me if I am wrong but the heater core should not be hot when the temp is set to cold. A heater core generates heat by allowing hot coolant to flow through it. If hot coolant were flowing through it, even if the blower wasn't on, the cabin would receive that warmth.
I honestly don’t know how it works on the JL. Some vehicles have eliminated the heater core coolant valve and the heater core is always hot. They control air temp by directing air flow rather than coolant flow.
 

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I honestly don’t know how it works on the JL. Some vehicles have eliminated the heater core coolant valve and the heater core is always hot. They control air temp by directing air flow rather than coolant flow.
I suspect that it is a lot cheaper to just direct air flow since all it consists of is a cheap stepper motor, a plastic flap, and some plastic gears.
 

bikenutty

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I thought I experienced this a week or so ago, but this morning, after about 45 mins drive to work, with the vent on (no A/C) set to 71 on both sides, I got blasted with hot air from the dash vents. I didn't touch any of the controls prior.
 

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Is anyone with a Sport or Sport S with standard system UConnect 3 (no automatic climate control) experiencing this problem also? Just wondering if it’s limited to the more complex HVAC software system.
 

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I went into my dealer yesterday to make an appt for the recall and mentioned the AC issue and the service advisor said he had heard no complaints complaints about this.....I think these Service Advisors are conditioned to say this by the dealer
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