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Unread 01-05-2014, 10:26 AM   #1
KillaJeep4569
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No Hot heat Please help.....

Hey guys, well It getting super cold and needed to use the heat a few weeks now. But It stopped blowing hot air. Sometimes it will blow hot for 5 seconds then get cool. I know my heater core is a little clogged cuz i can hear the anti freeze flowing thru.

Where should I start to look at? What do you guys think would need replacing?
Dont really wanna throw money into her unless it is really worth it. Thanks guys.

Truck warms up properly no issues there.
Radiator fluid is full, over flow tank was a little low.
Truck temp never goes above 220.
Heater core is a little clogged but has been since I got the truck.

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Unread 01-05-2014, 01:05 PM   #2
Oldfrog
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Maybe the blend door.

http://www.jeepforum.com/forum/f13/1.../#post14474612
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Unread 01-05-2014, 01:08 PM   #3
PolkaPower
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Do you have the auto climate control?
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Unread 01-05-2014, 05:43 PM   #4
jeeepguy
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Do a reverse flush on the core.
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Unread 01-05-2014, 06:02 PM   #5
NewbombTurk
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Could very well be a "air pocket" in the system.
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Unread 01-05-2014, 06:37 PM   #6
KillaJeep4569
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Quote:
Originally Posted by PolkaPower View Post
Do you have the auto climate control?
I believe I do.
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Unread 01-05-2014, 06:37 PM   #7
KillaJeep4569
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Quote:
Originally Posted by jeeepguy View Post
Do a reverse flush on the core.
I want to flush it out but dont have a powerful enough air compressor.
Is there another way to flush it?
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Unread 01-05-2014, 06:38 PM   #8
chiefjohnston
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Yeah, do a reverse flush. You can use the method I found using vinegar and lemon juice, blow out all the coolant with compressed air first, then fill the thing with the vinegar lemon juice, let it sit, the longer the better, blow it out and repeat, each time I did my son's (3 times) we got more crap out of it. Now it makes heat again! I drove it for two years without and finally had it with the thing, so, Good Luck! Changing the core is a major PITA!!!!!
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Unread 01-05-2014, 06:40 PM   #9
KillaJeep4569
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Originally Posted by chiefjohnston View Post
Yeah, do a reverse flush. You can use the method I found using vinegar and lemon juice, blow out all the coolant with compressed air first, then fill the thing with the vinegar lemon juice, let it sit, the longer the better, blow it out and repeat, each time I did my son's (3 times) we got more crap out of it. Now it makes heat again! I drove it for two years without and finally had it with the thing, so, Good Luck! Changing the core is a major PITA!!!!!
How powerful of an air compressor do you need.
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Unread 01-05-2014, 06:58 PM   #10
PolkaPower
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The auto climate controls malfunction commonly and can cause havoc with the blend doors. Mine has an intermittent problem where it will blow cold as ice one second then suddenly go warm. After disconnecting then reconnecting the battery it works normally again. Hasn't been a problem in a long time. I just need to go pull another unit from the jy
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Unread 01-05-2014, 07:14 PM   #11
KillaJeep4569
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Quote:
Originally Posted by PolkaPower View Post
The auto climate controls malfunction commonly and can cause havoc with the blend doors. Mine has an intermittent problem where it will blow cold as ice one second then suddenly go warm. After disconnecting then reconnecting the battery it works normally again. Hasn't been a problem in a long time. I just need to go pull another unit from the jy
I dont think it is the blend door problem.
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Unread 01-05-2014, 07:39 PM   #12
Uniblurb
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Quote:
Originally Posted by KillaJeep4569 View Post
I want to flush it out but dont have a powerful enough air compressor.
Is there another way to flush it?
If you're going to do a reverse flush remove the heater hoses from the front of your 4.0 since it's easy to mess up the soft copper/brass tubes coming out of an OE heater core or cause a leak where they're soldered on.

Then remove the hoses from the clips on the side of the valve cover and drain them down in a bucket. Then position the hoses up higher than the core add a can of fast flush with some warm water with a funnel until it comes out of the other hose and let it sit for a while with the hoses up.

Next drain the flush with the hoses down and flush out with clean water from a garden hose nozzle. Wear safety glasses since this flush can be nasty or you could use something less corrosive as already mentioned.

A low pressure air compressor should work fine and all you're trying to do is get the leftover liquid out. The hose pressure is a lot more important for removing the deposits/scale. Good luck!
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Unread 01-06-2014, 01:39 PM   #13
KillaJeep4569
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Quote:
Originally Posted by Uniblurb View Post
If you're going to do a reverse flush remove the heater hoses from the front of your 4.0 since it's easy to mess up the soft copper/brass tubes coming out of an OE heater core or cause a leak where they're soldered on.

Then remove the hoses from the clips on the side of the valve cover and drain them down in a bucket. Then position the hoses up higher than the core add a can of fast flush with some warm water with a funnel until it comes out of the other hose and let it sit for a while with the hoses up.

Next drain the flush with the hoses down and flush out with clean water from a garden hose nozzle. Wear safety glasses since this flush can be nasty or you could use something less corrosive as already mentioned.

A low pressure air compressor should work fine and all you're trying to do is get the leftover liquid out. The hose pressure is a lot more important for removing the deposits/scale. Good luck!
Ok. I have a 97 Grand cherokee and when I looked under the hood my heater core lines are side by side, do you know which way the flow is? And these lines connect into the water pump correct?

My hoses seemed a little squashy, and old. Should I replace them?

should One use like Bleach or Draino to unclogg the heater core?

Also with the Air hose, dont you want decent pressure so you blow out the gunk that has built up. Or will a garden hose do the trick?
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Unread 01-06-2014, 03:11 PM   #14
PolkaPower
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Disconnect both heater hoses. Do what he does. Not the part where he gets it in his face.

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Unread 01-06-2014, 04:19 PM   #15
KillaJeep4569
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i found that too, and watched it, I just dont know how much psi I would need from the compressor. mine may do 80 if that.
I am going to try this, and replace my thermostat.
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