Yet another lack of heat post
11-19-2017, 09:51 AM
#16
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Location: Arizona
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Year: 97
Model: Cherokee
Engine: 4.0
I haven't even started the Cherokee since my last post. I drove it yesterday and the heat was warm enough to be acceptable. However, it was 50 degrees outside. When time allowes, I will continue the research and make it better.
Bugout, Not yet. I need to buy one. I will say this tho, if the air from the heater box was even 2/3rds as hot as the heater hoses themselves, I would never complain about the heat.
Ken R
Bugout, Not yet. I need to buy one. I will say this tho, if the air from the heater box was even 2/3rds as hot as the heater hoses themselves, I would never complain about the heat.
Ken R
Wonder what happened to those days when humans were smarter than their car and heaters only had two settings... On and Off. Too many things to break now because we are just flat lazy. lol
Last edited by Bugout4x4; 11-19-2017 at 09:57 AM.
11-19-2017, 05:45 PM
#17
Senior Member
I'd look at the blend door. I had a problem with the temperature slider sliding over to heat but it wasn't moving the door properly.
11-19-2017, 07:10 PM
#18
CF Veteran
I did just the opposite. I added system flush and ran it for a bit before draining. When I was swapping my radiator I flushed the radiator really well before I put it in. I pulled it from my 99 and into my 98. Then I flushed the motor with the garden hose several times. I only pulled one heater hose during this. I didn't flush just the core.
I then proceeded to install new pump, t-stat and housing, metal heater hose tube, and upper and lower radiator hose. The heater hoses were not in stock locally so I didn't do them. I still didn't have much heat. It was warm enough to melt ice from the windshield over about 30 minutes but didn't change the air temp inside the Jeep. I was thinking it was the blend door because the **** doesn't move all the way to hot. But if I move the lever that the cable is connected to I can hear it closing tightly.
Once the engine is warmed if I leave the blower off then when I first turn it on it's hot and about 5 seconds in it then turns barely warm. So long story short I guess I should have and still should flush just the core.
I then proceeded to install new pump, t-stat and housing, metal heater hose tube, and upper and lower radiator hose. The heater hoses were not in stock locally so I didn't do them. I still didn't have much heat. It was warm enough to melt ice from the windshield over about 30 minutes but didn't change the air temp inside the Jeep. I was thinking it was the blend door because the **** doesn't move all the way to hot. But if I move the lever that the cable is connected to I can hear it closing tightly.
Once the engine is warmed if I leave the blower off then when I first turn it on it's hot and about 5 seconds in it then turns barely warm. So long story short I guess I should have and still should flush just the core.
11-19-2017, 07:10 PM
#19
CF Veteran
Dang raslfrasl double post!
Last edited by Waynerd; 11-19-2017 at 07:12 PM. Reason: Rrrrrrr. Double post
11-19-2017, 07:43 PM
#20
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Year: 97
Model: Cherokee
Engine: 4.0
I did just the opposite. I added system flush and ran it for a bit before draining. When I was swapping my radiator I flushed the radiator really well before I put it in. I pulled it from my 99 and into my 98. Then I flushed the motor with the garden hose several times. I only pulled one heater hose during this. I didn't flush just the core.
I then proceeded to install new pump, t-stat and housing, metal heater hose tube, and upper and lower radiator hose. The heater hoses were not in stock locally so I didn't do them. I still didn't have much heat. It was warm enough to melt ice from the windshield over about 30 minutes but didn't change the air temp inside the Jeep. I was thinking it was the blend door because the **** doesn't move all the way to hot. But if I move the lever that the cable is connected to I can hear it closing tightly.
Once the engine is warmed if I leave the blower off then when I first turn it on it's hot and about 5 seconds in it then turns barely warm. So long story short I guess I should have and still should flush just the core.
I then proceeded to install new pump, t-stat and housing, metal heater hose tube, and upper and lower radiator hose. The heater hoses were not in stock locally so I didn't do them. I still didn't have much heat. It was warm enough to melt ice from the windshield over about 30 minutes but didn't change the air temp inside the Jeep. I was thinking it was the blend door because the **** doesn't move all the way to hot. But if I move the lever that the cable is connected to I can hear it closing tightly.
Once the engine is warmed if I leave the blower off then when I first turn it on it's hot and about 5 seconds in it then turns barely warm. So long story short I guess I should have and still should flush just the core.
11-19-2017, 11:53 PM
#21
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Year: 1990
Engine: Renix 4.0
"System flush" lol I want to share something from the past that I do not recommend but does indeed work. First make up your mind that you are going to replace all the hoses on the system. Then pour about a half cup of muratic acid in the system and run it for about 5 minutes and then flush again. Then replace all the hoses. The results are absolute bare metal on every surface in the cooling system. lol
In my opinion the evidence points to corrosion in the heater core. It could also be that the heater core fins are dirty or corroded, which would insulate it and keep it from transferring heat.
If you are going to flush it with acid I would recommend isolating the heater core. If you disconnect it from everything then just about any acid will do the job (hydrafluoric, oxalic, sulferic)
You could try disconnecting the heater core hoses, plug one end, then fill up the heater core with a 25% acid and 75% water solution (depending on the acid). Make sure you wear gloves and and take safety measures. Let that sit for 5-10 minutes, then flush the heater core in both directions. If it is corroded and pitted bad enough on the interior this could cause a leak in the heater core, but that would really only be exposing a problem that already exists.
After it is flushed well make sure it is quickly reconnected with 50/50 antifreeze to keep it from oxidizing.
Or you could take out the dash and replace the heater core.
Last edited by craigjacob1; 11-20-2017 at 12:10 AM.
11-20-2017, 12:07 AM
#22
CF Veteran
I have a feeling white vinegar would work. Maybe it would need to sit in the core longer but is a bit safer at least. I use it a lot to clean stuff at work. Mostly hard water deposits and corrosion. Usually I use 5% but it is sold up to 10%. I've actually had metal, plastic and rubber pieces full dissolve by leaving stuff in it too long accidentally. It would take like 12 hours or more to do that though. I think maybe an hour or so soaking with straight 5% vinegar would do some good before flushing. I just might have to experiment with that.
11-21-2017, 09:08 PM
#24
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Year: 1996
Model: Cherokee(XJ)
Engine: 4.0
When you're at operating temperature, have you tried turning the heat all the way up and selecting "VENT"? Mine blows crazy hot air this way and I thought it might be a backdoor way to get heat until you can figure out your issue.
11-22-2017, 06:42 AM
#25
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Year: 1998
Model: Cherokee (XJ)
Engine: 4.0
Just an .02
On the surface this statement is easy to agree with. I applied that thinking to mine a couple years ago. Unfortunately, the gain in heat output was marginal at best. Changing the core is an annoying job and was not worth the effort. For my application, cleaning would probably have been a wiser choice.
On the surface this statement is easy to agree with. I applied that thinking to mine a couple years ago. Unfortunately, the gain in heat output was marginal at best. Changing the core is an annoying job and was not worth the effort. For my application, cleaning would probably have been a wiser choice.
11-22-2017, 07:13 AM
#26
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Year: 97
Model: Cherokee
Engine: 4.0
+1 This will probably work, but it is super risky. Flushing the entire system like this would be better utilized as a last resort to remedy overheating issues. It will take years off of the cooling components and possibly destroy gaskets. If you tried this in a porsche you could easily total the vehicle...
In my opinion the evidence points to corrosion in the heater core. It could also be that the heater core fins are dirty or corroded, which would insulate it and keep it from transferring heat.
If you are going to flush it with acid I would recommend isolating the heater core. If you disconnect it from everything then just about any acid will do the job (hydrafluoric, oxalic, sulferic)
You could try disconnecting the heater core hoses, plug one end, then fill up the heater core with a 25% acid and 75% water solution (depending on the acid). Make sure you wear gloves and and take safety measures. Let that sit for 5-10 minutes, then flush the heater core in both directions. If it is corroded and pitted bad enough on the interior this could cause a leak in the heater core, but that would really only be exposing a problem that already exists.
After it is flushed well make sure it is quickly reconnected with 50/50 antifreeze to keep it from oxidizing.
Or you could take out the dash and replace the heater core.
In my opinion the evidence points to corrosion in the heater core. It could also be that the heater core fins are dirty or corroded, which would insulate it and keep it from transferring heat.
If you are going to flush it with acid I would recommend isolating the heater core. If you disconnect it from everything then just about any acid will do the job (hydrafluoric, oxalic, sulferic)
You could try disconnecting the heater core hoses, plug one end, then fill up the heater core with a 25% acid and 75% water solution (depending on the acid). Make sure you wear gloves and and take safety measures. Let that sit for 5-10 minutes, then flush the heater core in both directions. If it is corroded and pitted bad enough on the interior this could cause a leak in the heater core, but that would really only be exposing a problem that already exists.
After it is flushed well make sure it is quickly reconnected with 50/50 antifreeze to keep it from oxidizing.
Or you could take out the dash and replace the heater core.
12-10-2017, 03:06 PM
#27
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Year: 1999
Model: Cherokee(XJ)
Engine: 4.0
Fast forward to yesterday. 28 degrees, snowing.
Jeep running at 207 degrees according to my scan tool. Heat barely warm enough to melt the snow on the windshield. Looks like Ken R is gonna have to replace the blend door!
Jeep running at 207 degrees according to my scan tool. Heat barely warm enough to melt the snow on the windshield. Looks like Ken R is gonna have to replace the blend door!
12-11-2017, 07:08 PM
#28
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Year: 1999
Model: Cherokee(XJ)
Engine: 4.0
Today I took the stepper motor/blend door--actuator off the heater plenum today. I tested the actuator motor, it works fine. I turned the blend door by hand and it flips to full hot and is solid when the door reaches the HOT position. Flipping it the other way to the full "Cold" position, it does not feel solid, like at full hot. The air at full cold is exactly that, full cold. The air at full hot is kinda warm, not even close to hot. Tomorrow I guess I will cut into the heater box plenum by the blend door and see if the door is broken or off it's axis.
The fun never ends!
The fun never ends!
Last edited by KenR; 12-11-2017 at 07:10 PM.
12-11-2017, 07:52 PM
#29
Newbie
No heat
OK guys,
99 Cherokee sport, made in 10/98 135K miles. Always runs at 210 degrees.
Heat has been only lukewarm since I bought it 30 days ago.
I searched and read as many posts as I could find about this issue.
I checked the flapper door and the stepper motor, the motor works as it should and when the door is at the end of it's travel, turning it by hand does not make it move more or "flex" any. The stop is solid.
I have flushed the heater core forward and backward, over and over and over using a garden hose. The first few flushes produced the most crap, the last few produced just clear water. The water comes out just as fast as it goes in. Then I flushed out the overflow bottle, whole lotta mud in it. I then replaced the water pump, the theromstat, and the coolant.
Still lukewarm heat. Both heater hoses are hot when the engine is up to temp.
Is it POSSIBLE that the heater core tubes are still plugged and the water from the hose kinda just goes across the end of the core and out the other pipe?
Ken R
99 Cherokee sport, made in 10/98 135K miles. Always runs at 210 degrees.
Heat has been only lukewarm since I bought it 30 days ago.
I searched and read as many posts as I could find about this issue.
I checked the flapper door and the stepper motor, the motor works as it should and when the door is at the end of it's travel, turning it by hand does not make it move more or "flex" any. The stop is solid.
I have flushed the heater core forward and backward, over and over and over using a garden hose. The first few flushes produced the most crap, the last few produced just clear water. The water comes out just as fast as it goes in. Then I flushed out the overflow bottle, whole lotta mud in it. I then replaced the water pump, the theromstat, and the coolant.
Still lukewarm heat. Both heater hoses are hot when the engine is up to temp.
Is it POSSIBLE that the heater core tubes are still plugged and the water from the hose kinda just goes across the end of the core and out the other pipe?
Ken R