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Unread 12-16-2010, 11:19 AM   #1
XJNut98
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1998 XJ Cherokee 
 
Join Date: Nov 2010
Location: Wilkes Barre, PA
Posts: 13
XJ heating problem

Ok I'm sure I just missed something stupid here but I thought I would check to see if anyone else ever ran into this:

My xj takes forever and a day to make heat. pretty much have to wait till it's fully warmed up to get lukewarm air. never gets HOT. just warm. I already backflushed the heater core and got good flow through it. anyone have any problems with their blenddoors not shutting all the way? only other thing I can think is that the coolant mixture is a bit on the antifreeze side and less water because I dumped half a gallon of pure into it before realizing it wasn't premixed. I don't see any sort of heater valve. hoses appear to be connected right. I doubt it's the t-stat because the engine gets warmed up good. I checked both sides of the core (inlet and outlet lines) with a infared thermometer and they're running about the same as the upper hose. all I can think is a partially blocked heater core or the blend door is allowing cold air past.. any ideas before I go ripping the dash out?

THANKS

also don't know if this would have anything to do with it but the head has been replaced within the last 6 months.

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Unread 12-16-2010, 05:14 PM   #2
djb383
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1998 XJ Cherokee 
 
Join Date: Jan 2010
Location: The Republic of TEXAS
Posts: 2,203
My guess is heat blend door. Think they're cable operated.
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Unread 12-17-2010, 05:51 AM   #3
careyhunt
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Join Date: Sep 2010
Location: killawog
Posts: 5
The blend door is driven by an electric motor. Look under the dash on pass side, you'll see the motor that runs the blend door( close to the center console). It has been said that they overdrive the door and either strip or break a portion of the door. Look under there and when you move the heat control from hot to cold and back, you'll see it rotating. If you see it moving but air dosen't get any warmer, remove the motor and inspect the shaft. Grab it and see if you can move it be hand. There is an easy cure on a website. Search for "heater treater" if you can't get the door to move.
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Unread 12-17-2010, 06:55 AM   #4
1armyguy
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1998 XJ Cherokee 
 
Join Date: Jul 2010
Location: Fort Dix, NJ
Posts: 68
Quote:
Originally Posted by XJNut98 View Post
Ok I'm sure I just missed something stupid here but I thought I would check to see if anyone else ever ran into this:

My xj takes forever and a day to make heat. pretty much have to wait till it's fully warmed up to get lukewarm air. never gets HOT. just warm. I already backflushed the heater core and got good flow through it. anyone have any problems with their blenddoors not shutting all the way? only other thing I can think is that the coolant mixture is a bit on the antifreeze side and less water because I dumped half a gallon of pure into it before realizing it wasn't premixed. I don't see any sort of heater valve. hoses appear to be connected right. I doubt it's the t-stat because the engine gets warmed up good. I checked both sides of the core (inlet and outlet lines) with a infared thermometer and they're running about the same as the upper hose. all I can think is a partially blocked heater core or the blend door is allowing cold air past.. any ideas before I go ripping the dash out?

THANKS

also don't know if this would have anything to do with it but the head has been replaced within the last 6 months.
I have a 98 as well and was having the same problem. I did a back flush on the heater core and made a big difference. Of course the jeep takes a while to actually warm up anyway but, I am now getting much better heat since I did the back flush. What you need to do is, remove the heater hoses from the engine that go to the heater core. the smaller one is the return line, that one should be on the bottom as it runs from the return line from the water pump to your heater core. That is the hose that you will need to run air through or a hot water hose. Be sure to have the other hose in a container of some type. I used a milk jug. Once you either blow out everything you can into the container, I poured some bleach into the return line until it was coming out of that same hose. Be sure to have the other hose out of the jug and put up higher then the heater core. Let that sit for at least an hour. Then go back and flush it out again, same as before. Then give it a good rinse. You can use a garden hose and let it run through. Be sure you have the other hose in your empty jug again. Do this a few times to be sure it's rinsed out until you get a good clean flow if clear water. You can do the bleach and rinse as many times as you need to. Just be sure to rinse out really good. Then reattach the hoses and use your new found heat.
Good Luck.
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Unread 12-17-2010, 09:24 AM   #5
XJNut98
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1998 XJ Cherokee 
 
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Location: Wilkes Barre, PA
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Quote:
Originally Posted by 1armyguy View Post
I have a 98 as well and was having the same problem. I did a back flush on the heater core and made a big difference. Of course the jeep takes a while to actually warm up anyway but, I am now getting much better heat since I did the back flush. What you need to do is, remove the heater hoses from the engine that go to the heater core. the smaller one is the return line, that one should be on the bottom as it runs from the return line from the water pump to your heater core. That is the hose that you will need to run air through or a hot water hose. Be sure to have the other hose in a container of some type. I used a milk jug. Once you either blow out everything you can into the container, I poured some bleach into the return line until it was coming out of that same hose. Be sure to have the other hose out of the jug and put up higher then the heater core. Let that sit for at least an hour. Then go back and flush it out again, same as before. Then give it a good rinse. You can use a garden hose and let it run through. Be sure you have the other hose in your empty jug again. Do this a few times to be sure it's rinsed out until you get a good clean flow if clear water. You can do the bleach and rinse as many times as you need to. Just be sure to rinse out really good. Then reattach the hoses and use your new found heat.
Good Luck.
I already flushed it. and don't use bleach for god's sake it will eat through the brass!! maybe yours is aluminum and you got lucky?
I'm pretty sure it's got to be a blenddoor issue. it's cable operated on this model. feels like it's getting hung up on something. I can't move it all the way to hot without the cable binding. Maybe some ******* dropped a pencil down the heating ductwork... wouldn't be the first time I've seen this
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Unread 12-17-2010, 10:01 AM   #6
1armyguy
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1998 XJ Cherokee 
 
Join Date: Jul 2010
Location: Fort Dix, NJ
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I know that you can see where the cable attaches on the passenger side if you look under the dash toward the center. I thought the same thing about mine and saw the cable moving fine with it attached to the door. Maybe you can unhook the cable and try moving it manually.
Good Luck
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Unread 12-17-2010, 01:22 PM   #7
XJNut98
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1998 XJ Cherokee 
 
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Location: Wilkes Barre, PA
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Quote:
Originally Posted by 1armyguy View Post
I know that you can see where the cable attaches on the passenger side if you look under the dash toward the center. I thought the same thing about mine and saw the cable moving fine with it attached to the door. Maybe you can unhook the cable and try moving it manually.
Good Luck
yea that's my next course of action. it's 20 degrees outside though so gonna have to wait till I can get it in a warm garage.
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