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Vladgmru, Automotive Electrician
Category: Jeep
Satisfied Customers: 2668
Experience:  I've been working with American made cars since 1992.
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2003 Jeep Liberty. Heater doesnt put out much heat. Plenty

Customer Question

2003 Jeep Liberty. Heater doesnt put out much heat. Plenty of air flow but never gets very warm.
Submitted: 7 years ago.
Category: Jeep
Expert:  Vladgmru replied 7 years ago.
Thanks for choosing JustAnswer.
My name is Vladimir.
First of all make sure your coolant level is OK.
The problem you described could be caused by a faulty thermostat that may stuck open.
If this is the case, your engine won't reach normal operating temperature and the heater will blow only lukewarm air.
It is also possible that the heater core is partially clogged, if this is the case try to backflush it.
We can back and forth on this thread, so feel free to ask for additional information.
Customer: replied 7 years ago.

Collant level OK. Engine operating temp njormal. How do u backflush heater core?

Expert:  Vladgmru replied 7 years ago.
Please check the following before back flushing.
Find the heater inlet and outlet hoses under the hood, start the engine and let it reach operating temperature, then feel the heater hoses. If both of the hoses are hot to touch, then you probably have a problem with a blend door ( temperature door) within the A/C-heater housing.
If one hose is hot while another is warm, then you mat try to back flush the heater core.
Disconnect the heater hoses and use a garden hose to flush the heater core.
Change water flow direction several times. If you have compressed air, you may want to alternate air and water applying.

Edited by Vladgmru on 12/8/2009 at 6:24 PM EST
Customer: replied 7 years ago.

Noty sure which hoses are the correct ones but the ones I checked appeared to go through the firewall just off center on the passenger side. 2 were metal and one was rubber. All 3 were on the passenger side just over the valve cover. All were hot.


Took a meat Thermometer and inserted probe into vent on dash. At higest heat setting it was only putting out 90 degree air. This is not enough to warm the cab when outside air is 15 degrees. I have had the jeep since new and the heater always put out plenty of heat. Had a crack in the radiator about a year ago. They replaced the radiator and top and bottom hoses. That was during summer so never really needed to use heater much until this winter.

Expert:  Vladgmru replied 7 years ago.
If hoses going to the heater core are hot, then I can assume that there is something wrong with the blend door or its actuator.