Here is where stand with my heater problem. 97 TJ 4.0 Had great flow with little to no heat. Flushed core (good) new radiator cap and radiator. Water pump has good flow. System has proper pressure. All solenoids work for direction of flow. Discovered that when heat is on high, the fan is pulling outside air through cowl opening. This lowers my temp of heat. To fix i covered cowl opening covered heater access inside of cowl with duct tape. (needed fixed as -10 sucks) I now have warmer heat but no flow. As my feet and body freezes i am ready to drive my TJ into a lake and buy a car. Any thoughts on what else it could be. I am thinking there should be a door above the blower motor. Also the blender door functions properly. Tired of being cold....
__________________ But the wisdom that is from above is first pure, then peaceable, gentle, and easy to be intreated, full of mercy and good fruits, without partiality, and without hypocrisy. James 3:17 (KJV)
So i am looking at the second image. Is there supposed to be a door there where it says recirculation door? I have nothing and can see the blower motor wheel when the cowl is off? I taped off at the top of the inlet. Does air need to pass through for there to be any pressure through the vents?
quick update....if any one cares....I pulled the blower motor. I cant see the heater core..stuck in a vacuum and got nothing out...returned jeep back to previous condition..decided I am going to buy a plug in heater to get through Happy Trails....The FJ Cruiser is what I am thinking of getting....
In a heater related problem that has me stumped, I have a97 Tj with the luxurious broken defrost actuator arm. Currently, I have a luxurious xl zip tie holding the defrost flap open (used like a coat hanger but the zip tie tucks under the windshield and is barely noticeable. Now, when set to the top vents (chest level) the defrost comes out smoking hot and the vents blow room temperature, at best. In looking at the pictures above, I'm trying to think if the air flow blender flappy could be my issue. Any insight?
Just to recap for anyone that thinks of something
heater core-flushed and reversed flushed 3x times is crystal clear both ways
heater hoses- equal temperatures
System has some heat just NO flow through ANY of the vents.
I'm a mechanic in the Army too. I think you are over looking something simple. The HVAC system is not very complex at all in our jeeps.
that is the key reason I am so frustrated. When I had great flow it was cool air. I discovered that I had no fresh air door thanks to PO!!! so I taped that off and the heat improved. but when the heat improved the flow decreased. UGH!! I am at the point of ripping all heat related components out of Jeep and putting in a custom heating system from a diesel. It will definitely NOT be similar to that of a HMMWV. I am so tired of being cold all day everyday.
Do you have a/c? If not, you don’t have the recirculation door. The only place for air to enter the HVAC unit is from the cowl. If you block that off there will be virtually no air flow as you describe. Without airflow the heater core will get hotter than if cold air is going through. Then you may think the heat is improved but not helping with the air flow you need.
Make sure the temp slider is moving the blend door all the way to make sure all of the airflow passes through the heater core. Any air passing around it will give you less heat.
Do you have any way to check the temp in the heater core compared to the temp of the coolant entering the top of the radiator?
If you do have a/c then you can maybe improve the heater by keeping the recirculation door open (when open the outside air is blocked). You can only get recirculation with the a/c on but if the temp control is all the way to hot no cold air will come through (assuming the blend door is working as it should).
RUBI i do not have A/C. That would explain my lack of flow. I checked operation of blend door, when moving slide i can see it move the arm. it feels like the door is closing completely. I will check this out on monday. I have to run out of town and am borrowing a friends car for moment.
You should be able to tell if the blend door is working. With the engine at operating temp (210║) & with the cowl opening unblocked, slide the temp slider from cold to hot. You should feel a definite change in temp. Maybe not as hot as it should be, but a noticeable change from the outside air temp.
I was researching the HEATER TREATER set up. not sure if it will help, but i wont be able to remove the dash till spring. Also i have been thinking about making a type of recirculation way of blocking off air access through cowl and making an opening inside the cab of the jeep. Have you ever seen a setup like this?
That just allows you to turn the coolant flow to the heater core off. I don't see how that will improve the heat output. The purpose is to keep the hot coolant from getting to the core to help improve a/c performance.
As for making your own recirculation opening, I was going to suggest that if all else fails. You could make a cover for the "new" opening for fresh air in the summer if needed.
so I got home from drill. I have my jeep in the garage and looked into the blend door and I disconnected the cable and manually moved the arm. makes the sound of it closing. The wife is suggesting that maybe the outside air is just too cold for the heater to heat the jeep.
When you move the blend door can you feel the temp change?
That is possible. When working properly they should do the job even in very cold weather. But here is something to consider, if the air is too cold to get fully heated by the heater core, the outlet hose should be almost cold or at least much cooler than the inlet hose. It is possible that the core is bad. Sometimes they just won’t transfer heat as they do when new. There have been cases too when the impeller in the water pump is shot & it won’t cause the engine to overheat, getting just enough circulation, I guess, but won’t circulate euough coolant through the heater core. I know you said the radiator flow is good but is the flow through the heater good? Just throwing out possibilities.
I was having similar problems in my 97 TJ. After a few hours......I correct myself, it was a few days of repair work and of course a few dollars spent....... I drove my TJ yesterday for 7 hours at -10 F and 30-40 mile an hour winds. My feet were toasty and my body was warm and I have a soft top.
I removed the heater assembly and replaced the heater core, resistor set, resistor set wiring, blower motor, foam gaskets and heater switch. I checked the blend door and all of the vacuum motors for function. I also replaced the vacuum line from the intake manifold to the heater assembly, mine was brittle and easily broke when I handled it. I found myself using some silicone to seal some areas on the heater box that I felt could leak cold air. All of this work was not a lot of fun, however my toes now thank me. I am somewhat spoiled because I have a heated garage to work in.
When I bought my TJ in January, I drove it home for 2 1/2 hours with no heat at 0 degrees. I flushed the heater core when I got it home, this only made for warm air coming out. When I pulled my heater core I found that it was leaking and a lot of the fins were missing. I also found signs of a mouse that found a warm spot in the vehicle for a while.
I recommend pulling the heater box, going over it with a fine tooth comb. Replace what needs to be replaced. The unit itself is fairly simple, getting it out can be challenging.