Soooo, I have done EXTENSIVE research on why my heat is blowing cold air and have only found answers to the problem when heat only blows at high RPM's but in my case the heat is ICE COLD regardless of RPMs or engine temp. I noticed I had small cracks in the radiator and hoped that this was the issue. So I went through the motions. Did a complete coolant flush and clean. Next day replaced radiator thermostat coolant and also flushed & back flushed the heater core. Water shot out both sides easily so the core is not blocked. (There is no fluid on the passenger floor from a leaked core and the carpet is clean as a whistle).. Heat turns on fine and and all fans are blowing on every setting but the air is just ice cold. Does anyone have any clue what the issue could be? hopefully something more simple than a complete heater core replacement? I AM FREEZING! lol :chillpill:
No heat at all!
- Thread starter Bboyyumm
- Start date
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dude1116
Full Access Member
Things to check are coolant level and if the T-stat was put in backwards. I believe that could cause it.
Thanks, but coolant level as well as engine temp is normal.. T-stat was definitely put in right side up.. lol .. Any other ideas?
van462
New Member
Could be the air control vanes. I'll have to look to see if the KJ has vacuum operated vanes or not. It could be stuck in just vent mode and not sending the air across the heater core.
Edit: Vacuum is only used to change the output flow ie. defroster or floor vents. There is an electric actuator that controls the blend vanes. It's between the fan and the heater core. I also read the temp control switch can be calibrated. Unsure what would cause a loss of calibration. Cycling the temp control should cause the air blend vanes to move directing air to the heater box.
Edit: Vacuum is only used to change the output flow ie. defroster or floor vents. There is an electric actuator that controls the blend vanes. It's between the fan and the heater core. I also read the temp control switch can be calibrated. Unsure what would cause a loss of calibration. Cycling the temp control should cause the air blend vanes to move directing air to the heater box.
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VAhlene
Full Access Member
Yea I would check the blend doors I know Jeeps are notorious for having them fail.
Thanks for everyone skipping the usual forum ****** bag protocol and actually giving me helpful advice!! This would NEVER happen on a 240sx forum..lol..Anyways I just took it to a local shop and the mechanic says its the the blender door actuator.. $700 parts and labor.. I am wondering if I should just attempt this myself? How difficult is this repair? Thanks again everyone..
streetglideok
Full Access Member
Can only guess your jeep is a '02-'04 model? Calls for 4.5hrs, which would likely mean a dash pull. The part isn't the biggest expense, it's the work getting to it. I haven't had to pull one, so I can't speak from experience on this chassis. I can say that few people enjoy pulling dashes, and people who have never done one would compare it to an IRS audit. Granted I have the tools for doing that kind of stuff, so I'm able to do it faster, but consider it an all day job, with a lot of screws to take out.
Billwill
Full Access Member
You can download the relevant KJ Service Manual here....explains how to fault-find the problem and how to get to the Blend Door assembly, if you have a 2004 model...use the 2003 download:
Index of /manuals/Jeep/KJ
Arigato gozaimasu! lol
Billwill
Full Access Member
Fuse 25 (10 A) on the fuse panel inside the cabin....if you downloaded the Service Manuals you should have the circuit diagrams!
liberty74
Full Access Member
Going thru all the trouble of removing the dash to fix the blend door might want to throw a new heater core in also. The dash has to be pulled for that also. Replaced mine last winter. Even with water running thru both tubes on the heater core it could still be plugged.
