Another luke-warm heat TJ

vito2772

vito2772

TJ Enthusiast
Joined
Aug 1, 2019
Messages
210
Location
Hudson Valley, NY
Hello all,

Now that we are balls deep into the winter season here in NY, I've had to start utilizing my heat in the TJ again.

I've been noticing the heat doesn't blow as hot as usual. Something else I have noted this winter season is that my temp guage falls JUST BELOW 210, for the couples years I've owned this TJ, temp has always been rock solid at 210. But just below didn't cause too much concern for me, but I noticed it. It also seems to dip a bit lower when stopped, and comes very close to 210 when driving.

Especially on morning where the temp is single digits or teens, the heat doesn't feel very hot at all, more luke warm. When the outside temp is above 25, seems to be blowing hotter.

My first thing I'm going to do is do a heater core flush this weekend. I hope that fixes my issues.

Previous winters the heat was so hot I couldn't even keep it that high for that long without boiling myself. Now I have it full blast with my hands in front of the vents to keep myself warm enough.

If the heater core flush doesn't work then maybe I'll check my thermostat, but other than that, what else should I be checking?

Thanks
 
vito2772 said:
Hello all,

Now that we are balls deep into the winter season here in NY, I've had to start utilizing my heat in the TJ again.

I've been noticing the heat doesn't blow as hot as usual. Something else I have noted this winter season is that my temp guage falls JUST BELOW 210, for the couples years I've owned this TJ, temp has always been rock solid at 210. But just below didn't cause too much concern for me, but I noticed it. It also seems to dip a bit lower when stopped, and comes very close to 210 when driving.

Especially on morning where the temp is single digits or teens, the heat doesn't feel very hot at all, more luke warm. When the outside temp is above 25, seems to be blowing hotter.

My first thing I'm going to do is do a heater core flush this weekend. I hope that fixes my issues.

Previous winters the heat was so hot I couldn't even keep it that high for that long without boiling myself. Now I have it full blast with my hands in front of the vents to keep myself warm enough.

If the heater core flush doesn't work then maybe I'll check my thermostat, but other than that, what else should I be checking?

Thanks
Click to expand...
Blend door- make sure it opens and closes- I don’t know a lot about the blend door set up on the TJ but that is common with a lot of vehicles

You have the right approach
 
AndyG said:
Blend door- make sure it opens and closes- I don’t know a lot about the blend door set up on the TJ but that is common with a lot of vehicles

You have the right approach
Click to expand...
I will definitely check that. When I turn the temp knob, I can definitely feel the air getting cooler and hot as I turn, but I will verify that it is opening completely for the heat when it is switched that way .
 
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vito2772 said:
Hello all,

Now that we are balls deep into the winter season here in NY, I've had to start utilizing my heat in the TJ again.

I've been noticing the heat doesn't blow as hot as usual. Something else I have noted this winter season is that my temp guage falls JUST BELOW 210, for the couples years I've owned this TJ, temp has always been rock solid at 210. But just below didn't cause too much concern for me, but I noticed it. It also seems to dip a bit lower when stopped, and comes very close to 210 when driving.

Especially on morning where the temp is single digits or teens, the heat doesn't feel very hot at all, more luke warm. When the outside temp is above 25, seems to be blowing hotter.

My first thing I'm going to do is do a heater core flush this weekend. I hope that fixes my issues.

Previous winters the heat was so hot I couldn't even keep it that high for that long without boiling myself. Now I have it full blast with my hands in front of the vents to keep myself warm enough.

If the heater core flush doesn't work then maybe I'll check my thermostat, but other than that, what else should I be checking?

Thanks
Click to expand...
please report back after you flush the heater core. I'm having the exact same symptoms
 
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You don't need no heater core flush... trim a foam floor pad and put it in front of your radiator. Bam. Heat.

fhoame.jpg
 
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Couldn’t you feel the two hoses and verify the heater core is good? Hot in and hot maybe a tad cooler out? That’s where I’d start.
 
Im kind of faced with the same issue . I just bought one of my old jeeps back (1999) and heat is not as hot as it used to be . I had changed the heater core and evaporator a few years back . I just flushed it out ( it was clean ), new heater hoses and thermostat. Temp now runs a little closer to 210 like it used to but heat is still not as hot as it should be . The air temp coming out is about 120. It has a slight radiator leak from the about 11 year old NAPA radiator. I just ordered a new water pump ,upper and lower hoses, cap and radiator. I removed the actuator on the blend door and it works but not real smooth when turning it by hand so it may not be working as smooth as it could but feels like it completes the cycle. Im curious as to hear how yours is working and how you determined it is working correctly if in fact it is . If the heat is no better after installing the parts on order I may look into the heater treater blend door option . I have used their doors on a ram years ago and worked great .
 
vito2772 said:
Hello all,

Now that we are balls deep into the winter season here in NY, I've had to start utilizing my heat in the TJ again.

I've been noticing the heat doesn't blow as hot as usual. Something else I have noted this winter season is that my temp guage falls JUST BELOW 210, for the couples years I've owned this TJ, temp has always been rock solid at 210. But just below didn't cause too much concern for me, but I noticed it. It also seems to dip a bit lower when stopped, and comes very close to 210 when driving.

Especially on morning where the temp is single digits or teens, the heat doesn't feel very hot at all, more luke warm. When the outside temp is above 25, seems to be blowing hotter.

My first thing I'm going to do is do a heater core flush this weekend. I hope that fixes my issues.

Previous winters the heat was so hot I couldn't even keep it that high for that long without boiling myself. Now I have it full blast with my hands in front of the vents to keep myself warm enough.

If the heater core flush doesn't work then maybe I'll check my thermostat, but other than that, what else should I be checking?

Thanks
Click to expand...
In Oneida County myself. For the state inspection, the 99 TJ threw a P1281 code. Basically means it needs a new thermostat, because it stays pretty well below the 210. Probably stuck open.


On the other hand, the 97 stays slightly below 210 and throws REAL hot air thanks to the new heater core.
 
vito2772 said:
Hello all,

Now that we are balls deep into the winter season here in NY, I've had to start utilizing my heat in the TJ again.

I've been noticing the heat doesn't blow as hot as usual. Something else I have noted this winter season is that my temp guage falls JUST BELOW 210, for the couples years I've owned this TJ, temp has always been rock solid at 210. But just below didn't cause too much concern for me, but I noticed it. It also seems to dip a bit lower when stopped, and comes very close to 210 when driving.

Especially on morning where the temp is single digits or teens, the heat doesn't feel very hot at all, more luke warm. When the outside temp is above 25, seems to be blowing hotter.

My first thing I'm going to do is do a heater core flush this weekend. I hope that fixes my issues.

Previous winters the heat was so hot I couldn't even keep it that high for that long without boiling myself. Now I have it full blast with my hands in front of the vents to keep myself warm enough.

If the heater core flush doesn't work then maybe I'll check my thermostat, but other than that, what else should I be checking?

Thanks
Click to expand...
Thermostat is stuck wide open
 
So a little update. After we had some 55 degree days and not reaching 210 temp as usual, I determined it is the thermostat.

Got a handful of paper gaskets and 195 thermostat ready to go. Came apart easy, cleaned up the mating surfaces and swapped thermostat.

Leak. Redid it twice with new paper gaskets, Everytime leaking. Not initially, but once the engine was on and under pressure.

Was gonna give thermostat RTV a try, removed the housing again, except this time the lower, smaller length bolt fell behind the fan shroud for the radiator fan.

Bolt is not visible, tried flexible magnet tip tool, tried snaking it out, shaking the car, it seems trapped in a terrible spot. I can see the "cup" of the fan shroud the bolt fell into is sealed, so it isn't going to come out the bottom.

Upon rolling the vehicle in gear, the bolt rubs up against the back of the house with the belt. I'm thinking the fan and shroud is going to need to be disassembled to get this thing out.

Sometimes the simplest jobs turn into the biggest headaches....

(Posted on mobile, may be formatting errors)
 
Okay so, today we managed to fish out the bolt by some luck. Long flexible magnet tool was able to fish it out.
So pumped.

Flushed the heater core while we had the hoses off, assembled all together again with only the paper gasket, didn't leak finally.
Heat is scorching hot now too, which is great. Just like it used to be. Very happy with the heat output now.

But I still noticed I am below 210 on temp, even lower than before I changed the thermostat. When the problem first started, the needle was barely touching the 210 marker when driving. Less when stop.

Is this anything I need to be concerned about? Previously, used to be rock solid 210 before I had the heating issue, but now it seems to hang here when driving and stopped.


20220213_194539.jpg
 
Different brand thermostats work differently. I recently swapped mine back and forth and the change was obvious. I wouldn't worry much about a wagging needle
 
My 2000 Sahara used to sit just below the middle of the gauge. Engine ran fine via OBD and the heater was unbearably hot. When they switched to the newer style gauges (PCI bus) everything pretty much went to dummy gauges. I think the odler models like yours (97-00) actually fluctuated with the temp. I could always tell when the thermostat opened. Check it with OBD if you’re worried.
 
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