2004 LJ with luke warm heat

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larry silver

New Member
Joined
Oct 30, 2018
Messages
5
Location
Indiana
Hello all. I'm at a hair pulling moment. I am suffering from low heat in the 2004 LJ.

So far to date and for some other reasons than lack of heat, I have replaced, the heater core twice, the water pump and 195 deg non fail safe thermostat, a radiator, all of the hoses (radiator and heater hoses). Last night was a heat/ac control panel, rechecked the blend door for free movement and also the blend door actuator for operation. Everything in the system has been replaced. To note I have also checked the fluid level and its full, I have checked and rechecked the floor vent and cowl vent actuator and I am stumped.

I get luke warm heat and its about 10 deg. here in Indiana.

I have also checked the temp of the hoses in and out of the heater core and at Idle its about 150-155 deg. (going from memory on this and I'm old so I might be wrong). It does rise in temp following throttle position. The same goes inside at the vents. At Idle its almost cold and does raise with revving up the eng.

Trying to think of other details.

With the fan speed set at low the temp is hotter and when on high it goes down, like the air volume is diluting the little bit of heat that is being put off from the heater core.

So yeah, I'm open for ideas!!!
 
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I know that some of the aftermarket heater cores, for me it was Spectra, do not give much heat. There have been several posts on here about this problem. I don't know if this is your problem, but a different brand core worked for me. Good luck with it.
 
Wheeling diver said:
I know that some of the aftermarket heater cores, for me it was Spectra, do not give much heat. There have been several posts on here about this problem. I don't know if this is your problem, but a different brand core worked for me. Good luck with it.
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The first was a spectra and the second I tried i forget the brand, but they looked identical. Thanks. I hate to pull the dash again, but eventually that may happen.
 
Spectra is one of the devil's brand names. Not only are their heater cores junk, so are their fuel pumps. I installed a Spectra fuel pump years ago and it failed within a few months.
 
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Jerry Bransford said:
Spectra is one of the devil's brand names. Not only are their heater cores junk, so are their fuel pumps. I installed a Spectra fuel pump years ago and it failed within a few months.
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I have been looking quite a bit and not sure what heater core is worth a crap. I think the second one I put in was a Crown auto.. With OEM being nearly impossible to find they are all junk from what I read.
 
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larry silver said:
It is, Its staying at a just a hair under the 210 mark.
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Then the low heat has to be caused by a bad heater core, plugged heater core hose, or the flapper door motor that opens the flapper to let the heat out is not working. The heater core is always hot in a properly functioning HVAC system, the flapper door is what lets that heat out into the passenger compartment or prevents it from getting out.
 
Jerry Bransford said:
Spectra is one of the devil's brand names. Not only are their heater cores junk, so are their fuel pumps. I installed a Spectra fuel pump years ago and it failed within a few months.
Click to expand...
Can you imagine the call..."parts department, Satan speaking, what in hell do you want? "

Heater core.

"Oh, it's pretty warm here, ours aren't that hot...no pun intended"

Also, who is the Luke in luke warm. What did he do?
 
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