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Old 12-06-2013, 08:55 PM
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2003 Wrangler heat problems

I have a 2003 Jeep Wrangler 4.0L straight 6, which was experiencing heat problems this past fall/winter. We have tried almost everything, and numerous mechanics have looked at it but the problem just doesn't go away.

So far, we have:
-put in a new heater core
-new radiator and cap
-checked all blend doors (passed)
-checked all of the coolant hoses
-checked head gasket pressure (passed)
-new water pump
-replaced blower motor resistor
-replaced the thermostat 4 times

We received the jeep from a mechanic, the heat worked for a day and the 4th cylinder spark plug started fouling, so we replaced the spark plug. After we replaced that, the heat stopped working after changing the plug. The fans work on all settings, and you can get a little amount of heat on the lowest fan setting, but anything above that and it feels like the a/c is on.

We have tried almost everything we can, and any ideas or help would be appreciated. Thanks!
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Old 12-06-2013, 09:38 PM   #2
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Flushed the heater core?

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Old 12-07-2013, 08:25 AM
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Flushed it several times before replacing it, and flushed it after it was replaced.
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Old 12-07-2013, 10:20 AM   #4
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Check to make sure heater hoses are on the correct way so coolant is flowing in right direction, some heater cores have restricting valves. I don't know if jeep uses them or not, Just a thought.
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Old 12-07-2013, 10:37 AM   #5
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For a heater to work you need

1) good water flow
2) the water must be hot
3) good air flow via heater fan
4) air flow directed thru the heater core and no blockage of air flow thru the heater

Check each item
For first remove core outflow hose at core connection and plug it. Attach another section of heater hose to core long enough to reach radiator cap and remove cap. Hold hose over radiator cap opening and run engine and verify you have good flow. Some systems have a valve in heater lines to shut off hot water when running ac.

To check that water is hot reattach heater hose run till normal operation temp and feel outside heater hose in and out of core

For airflow just feel force of air out dash vents

Finally verify air doors in proper position to direct air flow through heater core

Also make sure ac compressor not running when just on heat( not defrost or ac) setting

If it all checks you have to have heat
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2003 , heat , jeep , problems , wrangler

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