• Want to add an app icon for this forum to your mobile device's home screen? Check out this thread to see how.
  • Have an event you want to share? Check out the new forum event calendar and how-to use it in this thread here.
  • To both new members and existing members, please read this thread about posting your topics in the correct sub-forum. It makes my job (and my life) a lot easier!

Heater problem: very little warm air in cold weather

frankiebeckman

New Member
Joined
Nov 8, 2019
Messages
12
Location
76180
2002 Jeep Wrangler "X" 196,000 Miles: I get very little warm air in cold weather.
Both heater hoses hot
Blower works fine
A/C is very cold
A/C vacuum switch has been taken apart and appears fine
Blend door has been inspected and appears fine, moves completely to both sides.
Side note: I can not get air to come through the floor vents. I suspect that valve is not working.
 

Chris

Administrator
Staff Member
Joined
Sep 28, 2015
Messages
41,901
Location
Salem, Oregon
If you can't get air to come through the lower vents, usually this is a sign that you have a vacuum leak somewhere in the system and it's not allowing the floor vents to open all the way. Those can be very, very tough to find, and sometimes you need to use a smoke test in order to find small vacuum leaks like this.

As for not enough heat, when was the last time you changed the coolant and flushed the system? Is the radiator completely full?
 
OP
frankiebeckman

frankiebeckman

New Member
Joined
Nov 8, 2019
Messages
12
Location
76180
i installed a new radiator this summer and did a thorough cleaning of the system by using several rounds of "evaporust" then new coolant. Coolant is full
 

Goatman

TJ Addict
Supporting Member
Joined
Apr 23, 2019
Messages
2,006
Location
Upstate NY
Not trying to sound off base, but after the coolant flush you DID have good heat, but now that its colder outside you no longer have good heat? Or you never checked the system was working correctly after the flush?🤔
 

Jerry Bransford

TJ Guru
Supporting Member
Joined
Nov 9, 2015
Messages
12,563
Location
Escondido California
i installed a new radiator this summer and did a thorough cleaning of the system by using several rounds of "evaporust" then new coolant. Coolant is full
Ok but as Chris said above it sounds like your issue is probably vacuum-leak related. That you can't get air flow to the floor vents is a strong supportive symptom of that.
 
OP
frankiebeckman

frankiebeckman

New Member
Joined
Nov 8, 2019
Messages
12
Location
76180
Not trying to sound off base, but after the coolant flush you DID have good heat, but now that its colder outside you no longer have good heat? Or you never checked the system was working correctly after the flush?🤔
I have not had good heat for years, I've been trouble shooting this thing for years.
 

Goatman

TJ Addict
Supporting Member
Joined
Apr 23, 2019
Messages
2,006
Location
Upstate NY
Then a vacuum issue is most likely. Any idle or stumbling on acceleration?
 
OP
frankiebeckman

frankiebeckman

New Member
Joined
Nov 8, 2019
Messages
12
Location
76180
Ok but as Chris said above it sounds like your issue is probably vacuum-leak related. That you can't get air flow to the floor vents is a strong supportive symptom of that.
I agree, I've looked at all the lines (as best I could without removing the dash) and don't find a leak. when I remove the lines from what I think is the floor valve, the one down low drivers side, and put my fingers over the two lines i can feel good vacuum.
I tried reversing the lines, not easy to do with the connector on the end of the line (they appear to be murphy proff) and that did't help, also reversed the lines on the upper valve too.
At one point while messing with the lines the luke warm air came through the floor vents.
 
OP
frankiebeckman

frankiebeckman

New Member
Joined
Nov 8, 2019
Messages
12
Location
76180
I have even cut a hole in the duct just above the blend door and looked inside with a bore-scope and the door appears fine and moves from side to side.
 
OP
frankiebeckman

frankiebeckman

New Member
Joined
Nov 8, 2019
Messages
12
Location
76180
Is it possible that the heater core has developed a bypass within the core that allows the coolant not to go completely through the core. My logic says no, but that is the only thing that makes sense to me.
 

lowranger

TJ Expert
Supporting Member
Ride of the Month Winner
Joined
Feb 6, 2017
Messages
4,788
Location
Kelseyville, CA, United States
Have you back flush your heater core? I was having the same issue with not getting enough heat through my heater. I back flushed my heater core and had nice heat again from my heater.
P.S. Dirty nasty water came out when I back flushed it.
 
Last edited:
  • Like
Reactions: blacksun43

Baltimoreed

TJ Enthusiast
Supporting Member
Joined
May 18, 2019
Messages
510
Location
Aurora, NC
Do you get hot air out any of your vents? Don't want to sound flip but a bad or missing thermostat will kill your heat.
 

blacksun43

Member
Supporting Member
Joined
May 25, 2018
Messages
48
Location
West Texas
Have you back flush your heater core? I was having the same issue with not getting enough heat through my heater. I back flushed my heater core and had nice heat again from my heater.
How bad was the coolant before you swapped everything out? Chocolate milk colored coolant? Any overheating or higher than normal readings on the temp gauge? When I flushed and back flushed the core, everything seemed good for a while.

I’m not a technician, but I wonder if the heater core is toast. I’d pick up the appropriate heater core bypass parts in case it tries to leave you stranded. Only speaking from experience.
One key topic (of many) this forum has helped me with is the cooling system. 😀
 

lowranger

TJ Expert
Supporting Member
Ride of the Month Winner
Joined
Feb 6, 2017
Messages
4,788
Location
Kelseyville, CA, United States
The coolant wasn't that bad and no over heating problems.
Thanks for the info.
I back flushed it over a year ago and have been to Moab since then.
 
OP
frankiebeckman

frankiebeckman

New Member
Joined
Nov 8, 2019
Messages
12
Location
76180
Have you back flush your heater core? I was having the same issue with not getting enough heat through my heater. I back flushed my heater core and had nice heat again from my heater.
P.S. Dirty nasty water came out when I back flushed it.
I have flushed it several times over the years and I get clear water and good flow through it.
 
OP
frankiebeckman

frankiebeckman

New Member
Joined
Nov 8, 2019
Messages
12
Location
76180
How bad was the coolant before you swapped everything out? Chocolate milk colored coolant? Any overheating or higher than normal readings on the temp gauge? When I flushed and back flushed the core, everything seemed good for a while.

I’m not a technician, but I wonder if the heater core is toast. I’d pick up the appropriate heater core bypass parts in case it tries to leave you stranded. Only speaking from experience.
One key topic (of many) this forum has helped me with is the cooling system. 😀
The coolant was really bad before I R&R the radiator and water pump. After the Evaporust treatments I back flushed the heater core several times
 
OP
frankiebeckman

frankiebeckman

New Member
Joined
Nov 8, 2019
Messages
12
Location
76180
Have you seen this?
Yes, I watched this a year ago and checked my actuator and it was working correctly. As I stated earlier, I cut a hole in the duct and looked inside at the door with a bore scope and I could see that it was moving completely from side to side.