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View Full Version : My heat is luke warm at best.



Nicksdsm
10-02-2009, 08:49 PM
It's getting colder in the morning. When using the heat at idle and the engine fully warm, the heat is only luke warm at best. The heat gets warmer when driving at higher RPM's but it's not as warm as it should be and it just cools down when the RPM's drop. I just flushed out the coolant and changed the thermostat. I had my shop perform a pressure test and there was no leak. I've been smelling coolant since I bought my XJ (8 months ago). I though I might have a bad Heater core but I'm not sure. The temp gauge read normal all the time and does not drop or go higher them haft way. Does anyone have any ideas?

Mudderoy
10-02-2009, 10:22 PM
It's getting colder in the morning. When using the heat at idle and the engine fully warm, the heat is only luke warm at best. The heat gets warmer when driving at higher RPM's but it's not as warm as it should be and it just cools down when the RPM's drop. I just flushed out the coolant and changed the thermostat. I had my shop perform a pressure test and there was no leak. I've been smelling coolant since I bought my XJ (8 months ago). I though I might have a bad Heater core but I'm not sure. The temp gauge read normal all the time and does not drop or go higher them haft way. Does anyone have any ideas?

I bet it's the heater core.

Voldemort
10-02-2009, 11:25 PM
I bet it's the heater core.

May be a clog also.

TXstiGUY
10-03-2009, 11:21 PM
are you running a stock 195 thermostat or did switch to a 180 in the winter you want to run the 195 it makes a huge difference in heater output, at least it did on mine "thats the safety answer" :thumbsup:

Nicksdsm
10-04-2009, 12:33 PM
I replaced it with stock replacement 195 degree thermostat.

MrJCRod
10-04-2009, 07:51 PM
This a forum... we can all guess parts and some of us will look like heroes if we're right but come on... let's get some ideas on what to check and try and figure it out without just replacing parts... Did you check the temp on the heater hoses? One is an inlet and the other an outlet... From my experience a 20 degree difference is normal from inlet to outlet... anything more can point to it being the heater core being clogged... If that's the case it's a bit of labor to pull the dash and replace it so I would disconnect the heater hoses and use a garden hose with the end off of it and backflush the heater core... That has worked for me in my shop a couple of times and saved my customers quite a bit of money but the unfortunate few had to have new heater cores installed if they wanted better heat... Good luck with it...

Mudderoy
10-04-2009, 10:58 PM
This a forum... we can all guess parts and some of us will look like heroes if we're right but come on... let's get some ideas on what to check and try and figure it out without just replacing parts... Did you check the temp on the heater hoses? One is an inlet and the other an outlet... From my experience a 20 degree difference is normal from inlet to outlet... anything more can point to it being the heater core being clogged... If that's the case it's a bit of labor to pull the dash and replace it so I would disconnect the heater hoses and use a garden hose with the end off of it and backflush the heater core... That has worked for me in my shop a couple of times and saved my customers quite a bit of money but the unfortunate few had to have new heater cores installed if they wanted better heat... Good luck with it...

Thanks for the info. I was having heating issues last winter, but I was running a 180 degree thermostat. I have a high flow 195 in there now, so I am interested to see how the heater works this winter. If I still have issues I'll check the hoses are you describe. Hopefully an IR scanner will do the trick.

BlueXJ
10-06-2009, 01:10 AM
I have had heater issues in the past and they were all traced to a partially opening heater valve.

Nicksdsm
10-07-2009, 06:10 AM
Today is my first day off in 2 weeks, YAY. I'm going to check the heater hoses and flush the heater core. Where are the heater valves?

cheap jeep
10-07-2009, 09:25 AM
On my 92xj the heater valve is on the heater hose. you might be able to see it move by having someone run heat control on dash back and forth a couple times. on some you can move by hand to check operation or take out and put in splice tube to see if heater works then,but heat will have no control until reinstalled.

Nicksdsm
10-07-2009, 12:47 PM
I FIXED IT, YAY. OK, so I flushed the heater core with a garden hose. LOTS of crap came out, mostly rust. I forced water into both hoses one at a time, back and forth until the water came out completely clear ( 8 times each ). After I was done, I reinstalled everything and topped off the antifreeze. The heat now comes out extremely hot all the time. Thanks for everyones help.


Now on to the next problem.

Nicksdsm
10-07-2009, 01:07 PM
It only took 10 minutes, i pair of channel locks and a small amount of antifreeze.

Voldemort
10-07-2009, 01:17 PM
Told you it was a clog. Good job.

MrJCRod
10-07-2009, 06:17 PM
I FIXED IT, YAY. OK, so I flushed the heater core with a garden hose. LOTS of crap came out, mostly rust. I forced water into both hoses one at a time, back and forth until the water came out completely clear ( 8 times each ). After I was done, I reinstalled everything and topped off the antifreeze. The heat now comes out extremely hot all the time. Thanks for everyones help.


Now on to the next problem.

Good job... glad it worked out for you...

Mudderoy
10-07-2009, 07:25 PM
I'm going to do that this weekend.

Ruinator
10-26-2009, 01:19 PM
OUTSTANDING Threat...... Wed AM I am all over this! Starting to get cold.
Thanks guys!

Mike

GaryFlattery
10-29-2009, 08:56 PM
I did away with the heater control valve on my 93 xj. Go get you a 5/8 & 3/4 brass hose connector and do away with the junk plastic valve. It will unexpectedly rot and you'll all of a sudden lose all your coolant and hurt your engine.

Nicksdsm
10-30-2009, 08:45 AM
When I turn on the heat I can smell antifreeze for about 2-3 min coming from my vents. The smell goes away after awhile. I pressure tested my system and there were no leaks. does anyone know where the antifreeze smell is coming from when I turn on the heat? Where is the interior heat intake?

Mudderoy
10-30-2009, 09:02 AM
When I turn on the heat I can smell antifreeze for about 2-3 min coming from my vents. The smell goes away after awhile. I pressure tested my system and there were no leaks. does anyone know where the antifreeze smell is coming from when I turn on the heat? Where is the interior heat intake?

Oh man I want to know this one too. I assumed there is a small leak in the heater core and after a few minutes of air passing over the fins, and the leak, it evaporates and the smell goes away.

BlueXJ
10-30-2009, 10:22 AM
The heater core is behind and below the glovebox but to replace it requires removing the whole dash. That is the way it is on the Renix Heeps anyway. They are copper and rarely leak but that sounds like the only way to smell antifreeze.

cheap jeep
10-30-2009, 02:27 PM
I used to work in a radiator shop 40 years ago, we repaired heater cores also. I would guess that it has a small pinhole leak.

Nicksdsm
10-30-2009, 05:13 PM
I would like to start by replacing the heater core hoses. Can I replace the heater core hoses with out removing the dash?

Nicksdsm
11-28-2009, 09:06 AM
Anyone know where the interior heat intake is located?

DETOURS
11-28-2009, 06:08 PM
Vacum may be bad at the heater control sensor....

http://www.rockauto.com/catalog/moreinfo.php?pk=815449

Nicksdsm
11-28-2009, 08:32 PM
yeah, I'm still trying to find the heater control sensor. It's not under the hood.