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Interior Heating Up

7K views 14 replies 9 participants last post by  Blindaviator 
#1 ·
I am having an issue with the interior of my TJ heating up... At first I thought it was just radiant heat from the Cat under the passenger side but I am beginning to think it is more than that...

I think the cat will transfer some heat to the interior but not the amount that I am experiencing... Driving the jeep around town I don't really get any heat inside but if I hit highway speeds for more than a few miles it heats up fast inside the cabin... Doesn't seem to matter if the windows are open or closed and/or if the A/C is on...

I have looked all over the firewall (inside and out), the bottom side of the tub and anywhere else I think it could be coming from... So far I haven't found any holes or damaged seals...

One modification I did early on was to install water cutoff valves in the heater hoses to lessen the heat in the heater core and make the A/C cool better... With that cutoff I am thinking the heat couldn't be coming from the heater core but could air pressure be pushing a door open or losing vacuum causing a door to open be the cause??

I believe the heat is coming from the cooling fan in the engine compartment but just can't seem to figure out how it is getting in...

I don't know the heating and A/C systems on these jeeps very well yet...

Any suggestions on where to look??
 
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#3 ·
Any suggestions on where to look??[/QUOTE said:
Is your jeep a manual? (Mobile app, can't see your info) My 6 speed builds up a ton of heat and will warm the interior quite a bit. I still have the original carpet in, a lot of people with manual complain about the heat coming from the floor after they've removed the carpet. Other than heat shield or coatings, I haven't found any viable solution to that other than maintaining a healthy trans.
 
#5 ·
Auto trans.

I wouldn't think the radiant heat would come through the floor that fast. I drive out to my brothers house a few times a week and it will start getting heat inside after just a few miles. It almost feels like the heater is on and blowing out through the floor vents. I checked the mixer door cable and actuator and they work fine.

I have been looking at taking the seats out and putting down some Dynamat to repel the radiant heat inside. There is also a stick on heat shielding material good to 2000 degrees I have considered sticking to the cat heat shield to repel that heat a little more.
 
#4 ·
My TJ tub gets hot also. I believe that is just how they are. I have Nuropothy in my legs and feet. It gets down right painful when driving in the summer time. Having the AC blow out bi level helps when it works. That's another long story.
In 90+ temps the only thing that helps is removing the doors.

I think that my 1991 YJ that I bought new was even worse.
 
#9 ·
Carpet is still in it...

I can run around town all day and barely feel any heat coming into the compartment from the exhaust but when I hit the highway after a few miles it feels just like the heater was turned on... Hot air blowing across my legs similar to the floor heating vents...
 
#7 ·
The manual tranny even the crappy six speed has very little heat generation the heat comes from the hot exhaust including the extra heat added to the exhaust by the CATS

The tranny you have may effect how the exhaust is routed but automatics generate significantly more heat which is why they have lines to move the fluid to the radiator as their fluid is hot enough to transfer heat to the hot coolant in the radiator


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#8 ·
#10 ·
That is pretty much how mine is. I drive it on the highway about 60 miles every day. That will definitely heat it up quick. If I make a short stop it's even hotter when I get back in. Probably because I'm stopping the air flow.
Yesterday it was cool enough to need the heater. Only had it on for 5 minutes.
 
#13 ·
Check the rubber seal around the steering shaft. I had the same issue. when I lifted the tub to put in new body mounts it pulled the gasket out. It felt like the heater was blowing on my legs cruising down the highway.
I will check that and see...

Something I noticed today that could be at least part of the problem... At the back of the engine compartment is the plastic drain for the windshield and I noticed there is a small gap between the edge of the drain and the body... The fresh air intake for the HVAC system has a cover to keep the water out... I'm thinking that at highway speeds the air pressure in the engine compartment is pushing the hot air up through the gap and into the fresh air intake and maybe out through the heater vents in the floor board...

I am going to try to close the gap and see if that helps...
 
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