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I have a 2000 jeep wrangler when I turn on the heat or defrost I can hear it running but I get no heat. What could cause this heater coil, thermastat or something else maybe?

Heater runs but produces no heat

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  • Cars & Trucks Master
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Is coolant level full? To check if the heater core is circulating coolant, feel both heater hoses where they enter the firewall-both should be hot when car is at normal operating temperature. If only one is hot, look for a heater valve in the heater line-make sure it is open so the heater core circulates. Not all vehicles have such a valve, in fact, I think most don't have the valve, but you could check. The valve may be cable operated or vacuum operated to open and close. If no valve, and one hose is cold, there may be an air block in the heater core. Crack a line loose to get coolant circulating.
If both hoses are hot, it is probably the doors in the heater case not operating properly. Watch the door actuators when you move heat from cold to hot, and when moving from defrost to another setting. The temperature blend door is probably on the passenger side of heater case. These doors may be cable operated, vacuum operated, or electrical motor operated. If you watch for their operation, you might see or hear the problem with them not opening or closing properly.
Good luck.
If both heater hoses are hot

Posted on Jan 01, 2013


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SOURCE: 98 jeep wrangler no heat

Try this disconnect the heater hoses from the heater core use a hose to backflush the core. Then reconnect and try again.

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Have the cooling system pressure tested. If it holds pressure, that's a good thing. If it doesn't hold pressure, you may have a leaking head gasket. What may be happening is the crack in the head gasket could be blowing hot air into the cooling system causing it to overheat.

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SOURCE: Heater/AC only blowing out of defroster vents

Defrost is the default. Pull the heater control panel off and make sure the vacuum lines are connected to the control. My Jeep had the same problem cause I was messing with the radio. Hope this helps.

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SOURCE: 1999 jeep wrangler heater blower

you need to change the resister block for the fan. it is located on the heater duct near the fan... there is a connector on it and two or three screws holding it in.


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Posted on Feb 21, 2009

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