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99 XJ Heat Question.. Sorry I'm new

robdiddy

NAXJA Forum User
Location
MI
First and foremost I hope this hasnt been asked hundreds of times. I've long stalked this board of Great XJ Patriots and taken your lessons and applied them.

Now I must turn to the XJ Apostles...

1999 XJ Classic.. Heat feels like a cool spring breeze, sometimes a 75 degree breeze.. Then drops back to say 60 degree feeling. Thermostat changed it runs at the line before 210.

One day when my mom was in the hospital last week it got up to 210 as i was sitting in the car not able to stay in the emergency room. It got up to a glorious 210 and I had actual heat!!!

Turned it off for 10 minutes went back outside boom cold heat temperature isn't even showing 190.

Radiator Flushed... Anti Freeze appears normal in reservoirs heats back to being spring like.

WTF is happening?
 
A partially obstructed heater core would my first suspect.
 
A partially obstructed heater core would my first suspect.

Thats what I've been thinking.. today was the first day it was over 32 degrees and since I got income tax refund and it was nice out I was doing a tune up with my dad. I appreciate you.
 
I had heat issues recently with my '98 XJ. Reverse flushed the heater core and I have nice heat again. Very easy with a garden hose on medium pressure, and a catch bucket underneath. Took me 15 minutes. What flushed out was fairly nasty. Prior to that, the heat coming through the vents felt lukewarm if you closed your eyes and pretended.

Is your heat dial nob turning through the entire temp range or does it get hung up before max heat setting?
 
I had heat issues recently with my '98 XJ. Reverse flushed the heater core and I have nice heat again. Very easy with a garden hose on medium pressure, and a catch bucket underneath. Took me 15 minutes. What flushed out was fairly nasty. Prior to that, the heat coming through the vents felt lukewarm if you closed your eyes and pretended.

Is your heat dial nob turning through the entire temp range or does it get hung up before max heat setting?

Yeah it works normally
 
Funny you should mention that, mine does that. Has done for the last 10 years. Is there a fix for that?

Well, what year is your Jeep? I had this issue on both of my XJ's this winter. My 96 (old style climate control unit) wouldn't slide all the way left to coldest setting. It got hung up about halfway. Funny thing is, even though it slid all the way through the hot setting, it didn't get very hot. I replaced the entire climate control unit thinking that was the issue, the old one was cracked in several places when I took it out so I thought that was for sure the problem. I put the new one in and it still wouldn't slide all the way. Turns out it was the cable adjustment under the passenger side glove box. I used needle nose pliers to adjust the cable and now it slides through the full range and I have full heat.

On my 98 XJ with the updated dial type nob, mine still won't slide all the way to the hottest setting, it makes it about 70% of the way. When I first bought it last fall I got no heat, lukewarm at best. I backflushed the heater core like I said in my previous post and now it is "hot enough". I don't know how to adjust the cables on the '97-'01 style dials yet.
 
I've got a 98 as well. It makes it just to shy of full and then is "spongy" and won't click into the last full hot setting. Same cable adjustment for the dial type?
 
I've got a 98 as well. It makes it just to shy of full and then is "spongy" and won't click into the last full hot setting. Same cable adjustment for the dial type?

That's EXACTLY what mine does too. It's spongy then rebounds immediately when you let go if you try to force it toward the hottest setting. It's not the same cable adjustment as the older style, which is easily accessible under the glove box. Anyone know where the cable adjustment is - if there is one - on a 98? I wonder if the blend door gets hung up somehow and the cable is fine, hence the spongy feeling when you try to force it.
 
Look up broken blend door, later models had a huge issue of some sort with the blend door breaking. Mines early so I dont know for sure, but it should be 97+
 
The blend door overall seems to work, just can't nudge to that last hot position. I've lived with it for now and would rather keep living with it than digging for the blend door.
 
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