Heater core question

Steven Renich

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I have poor heat in my 03 Liberty. I have attached a page from the service manual with the diagnostic procedures. The coolant is correct and was changed early this year. One of the aluminum heater lines is much cooler than the other and it never really heats up.

The blower and controls all work. I tested the simply by listening to the HVAC box and moving the switch. I can hear it whir.

I back flushed the heater core using a garden hose and water does flow through it (although not really strong flow). I tried to test for blockage in the hoses/thermostat by blowing into the supply hose and coolant came out the return hose. So there was no obvious blockage that I could tell.

When I put it back together, there was no change. The "return hose" is still cool and there is very little heat.


Should I just replace the heater core?

Thanks.
 

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tommudd

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It could still be blocked or partially blocked
The way they are designed there is sort of a bypass that allows HOAT to flow through, but not clear through the heater core itself
Thermostat good ? ( and MOPAR brand ? )
 

rigid

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I have poor heat in my 03 Liberty. I have attached a page from the service manual with the diagnostic procedures. The coolant is correct and was changed early this year. One of the aluminum heater lines is much cooler than the other and it never really heats up.

The blower and controls all work. I tested the simply by listening to the HVAC box and moving the switch. I can hear it whir.

I back flushed the heater core using a garden hose and water does flow through it (although not really strong flow). I tried to test for blockage in the hoses/thermostat by blowing into the supply hose and coolant came out the return hose. So there was no obvious blockage that I could tell.

When I put it back together, there was no change. The "return hose" is still cool and there is very little heat.


Should I just replace the heater core?

Thanks.
I went through the same procedure on an 02' two years ago. I did have to replace the heater core. My not have been needed but I also did the blend door actuator while that deep into it.
 

Steven Renich

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My not have been needed but I also did the blend door actuator while that deep into it.
Rigid - Thanks for the advice. I am going to do that also.

Since I do have flow problems of some sort, I am going to replace the heater core and blend door actuator while "that deep into it". In addition, the thermostat and water pump are at the other end of the heater hoses, so I will take them off to check for blockages. They will also be replaced. I will also flush the entire cooling system.

Steven
 

gbennett21

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any luck im in the same boat i changed heater core and still didnt have any luck
 

Steven Renich

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OK. So here is the end of the story ....
I did the repairs above and am glad that I did. The antifreeze came out a dark greenish brown (wow, not good). I had put new antifreeze in when I put the engine in about a year ago, but did not flush it. The previous owner must have been using a different type of antifreeze. I wonder if that had anything to do with the heater core going bad?.

With the new heater core in, the heat works much better.

I was able to verify operation of the new actuator by removing the glove box, unplugging the fan and putting my hand on the actuator behind the glove box. I can hear and feel it move when I turn the temp control.
 

nohitter64

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I didn't have heat right after changing the heater core. I had to burp the system well to get the air out since I had a new radiator and a new heater core. Once I did that the heat poured out like a furnace.
 

gbennett21

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@gbennett21
What are the current symptoms? Give us some details and we will try to help you out.
replaced heater core water pump radiator thermostat twice. one none mopar last one mopar. car doesn't over heat but i get no fluid to new heater core small hose 5/8 to heater core i fill heat and pressure. 3/4 hose cold no fluid. if i pump hose (squeeze it) i get fluid and some heat. but it disappear fast. i can get it warm if i rev engine 3500 rpm. but soon as i return to idle heat goes. i watch heat coming from vent with meat probe. so i can see heat goes up and down. temp goes from 70° to 120°. i can get it to heat up but loose it as soon as i drive around or stop squeezing the 3/4 hose to heater core
 

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