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Unread 01-03-2008, 12:38 PM   #1
willhf1011
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No Heat

The blower for heat and air in my jeep works just fine and i get a good flow of air but when i turn the heat on it still just blows cold air. any thoughts on this? would it be a bad heater core? or maybe no coolant flow to the core?

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Unread 01-03-2008, 12:55 PM   #2
Hockey1
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sounds like the heater core. try doing a flush of just that. do it forward and reversed. use a garden hose or take it to the carwash. just dont squeeze the trigger, it has to much pressure and will destroy it.
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Unread 01-03-2008, 12:56 PM   #3
timatoe
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I'd venture to say the heater core, but maybe the thermostat as well. May try that first as they're cheap and way easier to change out than the core.
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Unread 01-03-2008, 01:06 PM   #4
EABiker
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Also check the actuator cable that open/close the door to the heater box; if disconnected, it blows cold air no matter what!
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Unread 01-03-2008, 03:50 PM   #5
Jeep25
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Quote:
Originally Posted by EABiker
Also check the actuator cable that open/close the door to the heater box; if disconnected, it blows cold air no matter what!

Right. Make the the rod below the dash on the passengers side is connected to the loop.
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Unread 01-03-2008, 04:36 PM   #6
kloppk
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Check/do the following in order..

1) If the engine temp doesn't come up to about 180-210 then you have a bad thermostat. Replace with a 195 degree thermostat.

2) Check the temp of the two heater hoses with the Jeep running, up to temperature and the heater blasting. If both hoses are cool or 1 hose is cool then you have a blocked heater core (or less likely a blocked hose). If both hoses are hot then you have a problem with the temp controll to blend door connection or operation.
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Unread 01-03-2008, 04:45 PM   #7
jbierschwale
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Quote:
Originally Posted by kloppk
Check/do the following in order..

1) If the engine temp doesn't come up to about 180-210 then you have a bad thermostat. Replace with a 195 degree thermostat.

2) Check the temp of the two heater hoses with the Jeep running, up to temperature and the heater blasting. If both hoses are cool or 1 hose is cool then you have a blocked heater core (or less likely a blocked hose). If both hoses are hot then you have a problem with the temp controll to blend door connection or operation.
X2!

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Unread 01-03-2008, 05:41 PM   #8
HOLLYWOOD6973
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I just had the issue on my 95 bought a heat core for $35.00 @ Pepboys now It works awesome!
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Unread 01-03-2008, 06:21 PM   #9
JJ Jeep
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Just finished flush

Had the same issue on my 90 YJ. Took heater core hoses loose from the engine and used garden hose to flush. Gunk went everywhere. Flushed until the water ran clear. Connected the hoses and have a heater that will cook an egg now..

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Unread 01-03-2008, 06:57 PM   #10
bharris68
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To perhaps clarify what JJ mentioned: It sounds like he disconnected the hoses at the ENGINE side - NOT at the firewall Meaning that you had the benefit of the hoses to work with and were not twisted up against the firewall trying to force the hose into the core tube.
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Unread 01-03-2008, 08:52 PM   #11
Grape Ape
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Quote:
Originally Posted by bharris68
To perhaps clarify what JJ mentioned: It sounds like he disconnected the hoses at the ENGINE side - NOT at the firewall Meaning that you had the benefit of the hoses to work with and were not twisted up against the firewall trying to force the hose into the core tube.
But then he wouldn't get a chance to get his knuckles busted up and get all cut up on the parts he has to twist past.

Even better would be to look for a radiator flush kit and hook it into the disconnected hoses. That way you have a connection to twist the hose into.
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Unread 01-03-2008, 08:55 PM   #12
timatoe
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Quote:
Originally Posted by Grape Ape
Even better would be to look for a radiator flush kit and hook it into the disconnected hoses. That way you have a connection to twist the hose into.
X2 and they're cheap too.
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Unread 02-22-2012, 09:40 PM   #13
y87j
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Quote:
Originally Posted by JJ Jeep View Post
Had the same issue on my 90 YJ. Took heater core hoses loose from the engine and used garden hose to flush. Gunk went everywhere. Flushed until the water ran clear. Connected the hoses and have a heater that will cook an egg now..

JJ Jeep
Could you show pics or a diagram on how to do this?
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Unread 02-24-2012, 11:18 AM   #14
YJtuttrain
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is the actuator cable located right behind the heater switches in the dash? My YJ just randomly started blowing cold air, heater core was replaced already...I just fixed the headlight switch under the steering column, wondering if I knocked something around when I was in there..
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Unread 02-24-2012, 11:48 AM   #15
Turtlecon
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Could someone take a pic of the electrical wires connected to the heater box under the passenger side? Should be 3 wires connected to a plug. I think mine are in wrong order because the heater won't turn on at all, even with all vents open.
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