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!