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Discussion Starter · #1 ·
I have a 97' wrangler and the heat is not working (and it is getting extremely cold). I have installed a new radiator, thermo, and thermo housing and the jeep is holding 210 degrees all the time so it appears that the thermostat is working. Does anyone know of anything that will keep the heater from working. It blows air that is luke warm but will not get warm or hot. Also, all of the levers on the dash seem to be working fine and they don't have any play or loosness to them. Any info would be awsome! thanks
 

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Heater Core
 

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Take a look under the dash just to the right of center line. You will find where the end of the temperature control cable attaches. It opens and closes a door that directs air either through the heater core or bypasses it. Use your hand and push to the direction needed. See if that helps. Mine never really shuts off the heat with the dash control and I have to manually move it to get just cold air. You may have the same problem in the "other" direction. Does'nt hurt to try.
 

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Discussion Starter · #6 ·
The first thing i checked when this occured was the coolant. It was o.k. and last night i checked the vent cable and vent doors and they were o.k.. usually a core will either stop working completely, leak, or clog and cause over heating, this is what is stumping me. i guess i will start with the core and go from there but thanks alot for input. :thumb:
 

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I would burp it like Gripguru said it may just be a bubble.
 

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The first thing i checked when this occured was the coolant. It was o.k. and last night i checked the vent cable and vent doors and they were o.k.. usually a core will either stop working completely, leak, or clog and cause over heating, this is what is stumping me. i guess i will start with the core and go from there but thanks alot for input. :thumb:
Like most opinions, it may be a bubble which would stop the hydrolic's from moving the coolant's pressure, this may be a dumb question but have you checked for an inline shut-off valve or leaves in the intake opening for blockage?
You would know from the volume of air movement. If it is a clogged heater core it wouldn't cause overheating per-say, due to the volume of coolant running thru the core. If it is a clogged heater core from silicone, calcium deposits or whatever, try running water in the return hose either by reversing the hoses or a garden hose which would be the best if there is blockage.
 

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You should try driving a 70 CJ5 with little or no heat.....to small of a blower motor.

I would check for air blockage and flushing the whole system and then new coolant. Just my $0.02
 

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I took my '98 in on warranty because the heater would not put out any heat and they told me it was working fine.

I think the older TJs just have junk heaters.
 

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Hi,

Kinda a long shot, I'm not super familar with the TJ's, but you might check and see if it's got a micron in cab filter, had a friend with a late model dodge truck, with no air flow and it was just the filter.

another thing, is it a soft top, doesn't hurt to make sure that nothing is open and drawing the warm air out.

Other than that make sure that there is no obstruction to the air intake on the cowl.

-my 2 cents
 

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None of the Wrangler line has a micron filter that I'm aware of. That's a bit too Mercedes for the TJ.

The air bubble's a good idea. If you go to efforts to keep the fluid uncontaminated, you could drain your system, make sure the hoses are run in an unusually high path to prevent a loop seal, then refill with the same fluid.

After that, I'd lean on the heater core or a switch failure on your dash. A switch broken on the inside, I mean. Though it seems you'd be able to feel or hear that.

-Mikey-
 

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The system seems complicated but it is a fairly basic setup.

If you are full on coolant, no bubbles and the heater care is good. It will make heat.

If that is in good working order, what is left is all of the heater controls, switches and hardware in the heater box.

If you can get to the heater core without spending all day removing parts, I would get the motor to operating temperature, then feel the heater core to see if its warm.

Check both heater hoses to see if they are getting up to temp. one hot, one cold may point to a clogged heater core. If you find out the heater core is warm with the engine up to temp, you know you have control problems on the inside.
 

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Can I hijack this in a similar direction?
Difference being I have heat, gravity feed is plenty hot.
My core has cracks in the plastic housing (1990 Cherokee), and I can feel cold air blowing through it, when the rig/heater is off, why?
Doesn't appear to have a fresh air feed (hole) on the firewall side.

Heater fan works temperamentally. Motor side connections are good, little relay sumbitch thing that plugs into the assembly on the interior doesn't seem to affect fan operation one way or the other, when I have a fan, unplugging doesn't affect fan op.
Fan seems to work best when car is cold, freshly started.
Occasionally it will stay on after car warms up and I have a heater for 15 minutes or so.

My guess is the fan is worn out, and as it heats up, the contacts that are barely connecting on the inside, quit due to expansion, and the contraction when fan parts are cold gives it an electrical connection.

Could I be close?
Would an ohm meter tell me if that is the case?
 
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