So how do you fix the hvac blend door problem? Difficult?

[jeepguy4276]

My heat doesn't really work but the cooling system is all good. I've heard that others have had this issue and it's the blend door. Do how do you fix it? Is it hard? I'm wondering when I want to tackle it.

 

[tjkj2002]

If you have to replace the blend door the whole dash has to come out to access the HVAC box and the HVAC box also has to to be removed from the KJ.You also have to have the AC evac'd,then recharged when all done.

Book time calls for like 7.5 hours not including the AC evac and recharge.

 

[jeepguy4276]

If you have to replace the blend door the whole dash has to come out to access the HVAC box and the HVAC box also has to to be removed from the KJ.You also have to have the AC evac'd,then recharged when all done.

Book time calls for like 7.5 hours not including the AC evac and recharge.

Ugh. That sounds like a mess. Is the door the problem or is it some vac solenoid on the evac assembly? I can't imagine the actual door would break. Is it a easy to get part or dealer only special order type thing?

The a/c doesn't hold anything right now so that's not an issue. Po disconnected the lines at the condenser I found out.

It sounds like this is a common problem. Any ideas as to what the problem is? Anyway to prevent it?

I'm assuming that's the problem, I'm not sure what else it could be other than maybe a bad core but there is no leaking, smell, and it's flushed. This is the only thing I knew for sure it needed when I bought it, since it was cold out. The po said he hadn't had it looked at but is sure the blend door is not the problem. This leads me to believe he had it looked at and was told it's the blend door, since most people don't even know what a blend door is. Lol. So I bought it knowing it needs some repair anyway.

 

[tjkj2002]

Failing blend doors is a rare thing for a KJ,common on a dual zone WK though.The blend door is controlled by a electric motor,sadly the dash still has to be removed to change that also.

The mode doors(IE floor,vent,and defrost selections) are controlled by vacuum but the blend door is electric.

 

[VAhlene]

This happened to me in my old Grand Cherokee. I used the Heater Treater fix, its a kit you buy online and the fix is made through the glove box instead of removal of the dash. It worked really well for me as they use upgraded blend doors so this wont happen again. It's a good alternative if you don't feel like paying to get the whole dash removed and a/c recharged and all that good stuff. Looking on their website though I dont see a kit for the KJ. you could maybe call and see if they can help you out.

 

[jeepguy4276]

If not the blend door what else could it be? New radiator, thermostat, hoses, flushed, no leaks or coolant smell, no hazing on the window, and the heater hoses to and from heater core are warm. It runs in the center of the temp gauge. Can't think of what else it may be.

 

[first&lastKJ]

Our 02 has the same issue, dealer said it's the heater core. Over a grand to replace. Both heater hoses are hot.

 

[jeepguy4276]

I suppose the heater core comes out with the hvac assembly anyway. If it's a bad heater core might as well do both. Am I wrong in thinking the heater core is pulling the same stuff out to fix?

 

[first&lastKJ]

Yes, the dash must be removed to get the heater core out.

 

[Billwill]

Bear in mind that the vents use Blend doors and a vacuum system that operates from a small thin rubber pipe coming off the intake manifold and going into the cabin...if this pipe comes off or is torn then you may have some problems.

 

[LibertyFever]

My "mode door" is slow to operate. Does anybody have a tip on how to fix it? Maybe I should chase the vacuum lines & look for a leaky hose.

 

[jeepguy4276]

New discovery on lack of heat. Help!! It's freakin' cold out!
I cut a hole in the heater box so I could see what's going on. The large door that's closest to the glove box opens and closes when the knob is turned between hot and cold. This should be the blend door shouldn't it then? I was under the impression the blend door was close the the firewall. The air also changes between vent, defrost, floor, etc when that knob is turned as it should. The hoses going to/from the heater core are both hot. New radiator, hoses, thermostat, res tank cap, and a fresh flush and heater core flush with the fill of g-5 coolant. The radiator hoses both seam to have coolant flow thru them.

So what is going on? Why am I not getting heat???

Help!!!!!

 

[Snail Farmer]

Heater core is probably flowing but partially plugged. Seen quite a few people lately on here that flushed theirs with no results.

 

[mightybeet]

only time i didnt feel heat was when i just changed my waterpump and had more air than coolant. after all the air came out and filled up with coolant the heat came back.

 

[jeepguy4276]

Is there a way to get all the crud out with flushing then or does the heater core need to be replaced? System has been bled a couple times and should definitely be air free.

 

[Snail Farmer]

I believe it needs to be replaced.. the way it's designed I don't think it can be flushed completely.. anyone else want to confirm this?

Sent from my HTC One using the power of Mary's purse

 

[KJScott]

I'm sure you could try to flush it but you would need to get all the crap out of there that you knocked loose. perhaps flushing both ways the shop vac out the remaining water. You might be creating a leak though, which means replacement, or buy good Alpinestars Gloves!

 

[profdlp]

Maybe an off-the-wall idea, but I wonder if it might work to set up a closed loop and let it circulate a good flushing solution for hours or even a day or two. I'm thinking of how parts washers can clean up stuff over time that you'd have a hard time cleaning any other way. Think Colorado River style cleanup.

 

[CzarKJ]

Maybe an off-the-wall idea, but I wonder if it might work to set up a closed loop and let it circulate a good flushing solution for hours or even a day or two. I'm thinking of how parts washers can clean up stuff over time that you'd have a hard time cleaning any other way. Think Colorado River style cleanup.

Wouldn't be difficult if you could get your hands on a peristaltic pump and a little bit of tubing and fittings.

 

[dee696]

heater core dude!!!!!!! i had the exact same problem last summer...lucky for me,i found it before winter...1000$ at dealer or 80$ if u do it....a long day of un-screwing a bunch of bolt,scraching arm,et sweating and ur done!!! u can try to flush it before,but i dont think it will help that much.... and i did it without removing the steering colums,but the dash itself has to be un-screwed at 100%...a lot of pain,but im not a mecanic at all,and still did it...but don't do that outside...it's a long job...