Also doing IR on heater core hoses. Starting at engine back temp is good when i got to bends in hoses right at firewall and temp drops. Had good flow through hoses when back flushed. Could it be bad hoses?
Cool Heat At Idle, Hot Heat At Higher RPM's
- Thread starter PhillipA
- Start date
I doubt the heater hoses are bad. I have seen lower radiator hoses collapse, but never a heater hose.
Why don't you try disconnecting the heater hoses from the heater core, install a coupler between the hoses. Then go drive it.
Measure the hoses with the thermometer and see what your temps are.
If they are equal, your problem is the heater core.
You can attempt to try and test the flow out of the heater core.
disconnect the lower hose at the return pipe. install a rubber plug on the pipe
point the heater hose into a bucket and have someone start the jeep. see what kind of flow you have coming out of the heater core.
you may have decent flow though the core using pressure from a garden hose, but no flow while using pressure from the cooling system.
With the lower heater hose disconnected you can attempt to run a wire coat hangar thru the coolant pipe to see if its blocked.
Just trying to throw some ideas out there.
What brand heater core did you install.
I took to a radiator shop to change out heater core. Not sure what brand they used. Probably one from Napa. Thanks for the tips. Tried everything else. LOL!!!
If it helps i will. I know it does for looks because i dont like it. But the grill has been hit and bent in. Trying to fix heat before i have to but the whole grill. Looks like the whole front end is one piece.
I checked IR temp at firewall where heater core hoses go in and temp was allot cooler than at motor. The AC lines and accumulator was ice cold. I unplugged my AC and my vent heat went up to 125 instead of 100 with A/C plugged in. ?????
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Provocative. That would definitely help to explain why your heat wasn't so hot. Time to check and see if you are getting a load on the compressor clutch when you are using heat only.
Yes. did you figure anything out yet?
I get a 10 degree drop when switching from vents to defrost. 160 vs 150.
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I also changed out the heater core when doing the evaporator core and now I am in the same boat. I have also tried about all of the same things, except I had already replaced all of the cooling system before the heater core. If anyone can figure out what to do to fix it it would be greatly appreciated.
When running on defrost ac evaporator that is right beside heater core hoses were ice cold. I unplugged evaporator and increased my heat by about 10 degrees. While i was unplugging evaporator i also tried one more time to burp coolant system. The reason i did that is because even after driving for about 30 minutes i still did not have any pressure in top radiator hose. Pulled jeep up on steep incline and took off radiator cap and started engine "after it had cooled down of course" turned heat on high and defrost. Kept squeezing top radiator hose and got allot more air out of system and also another member had stated that he had loosened heater core hose connected to metal tube that runs into water pump, slid a small screwdriver between hose and tube and i also got more air out that way. Be careful doing that because hose can come completely off metal tube. I think i had MAJOR air in my system because now i have 145 out of defrost. Still have evaporator unplugged.
145 out the defrost vs. my 150. I would be able to live with that.
The compressor should run/cycle when you have the defrost on. This is how the system removes moisture from the passenger compartment.
I'm going to give this a try since I've had the same issues after replacing the cooling system
Swamp Yankee
TJ Enthusiast
T-Man LolaTJ
New Member
First Post, read this entire thread and I believe my wife's TJ has the exact issue. Had the HC replaced only to have the heater produce heat with higher RPM's. Checked the usual suspects, mixer box actuator, vacc controls, AC off, tried to burp the self burping system etc.
Wasn't until I read through this entire thread I started to understand the "self" burping system can take time, like weeks. So I jacked up the front of the TJ to make the radiator cap the high point and re-burped the system. I haven't taken it out on a drive yet, but heater at an idle is MUCH better.
Shop replaced the water pump and T-stat. I'm wondering if the new T-stat doesn't have the little hole?
Wasn't until I read through this entire thread I started to understand the "self" burping system can take time, like weeks. So I jacked up the front of the TJ to make the radiator cap the high point and re-burped the system. I haven't taken it out on a drive yet, but heater at an idle is MUCH better.
Shop replaced the water pump and T-stat. I'm wondering if the new T-stat doesn't have the little hole?
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