2000 Cherokee Sport.

Alright, we've had this thing for 3 years now, and neither the heat or a/c have eve worked worth a damn. The blower is strong.

The A/C will work for about 5-10 minutes quite well, then get warm and humid feeling. Sometimes it'll cycle back to cold. Usually not. Since it's not normally driven for more than 10 minutes at a time, we usually just don't bother.


The heat is the bigger issue. It's never worked well. It'll get lukewarm-ish. Putting the blower speed higher than "2" makes the speed of the air overwhelm what little warming properties it had.

I've flushed the heater core, and what came out was dirty, but not impressively so or chunky. I wasn't able to get particularly high pressure through it, so take that for what it's worth.


What i have noticed is that with the truck "ON" but not running, when i twist the temp control ****, i can't hear anything moving under the dash, so i don't THINK the blend door is moving. IF the blend door is not moving, would this actually cause BOTH of my issues?

And if the blend door is not moving, how do i pinpoint the problem to the blend door motor itself vs. the HVAC panel controls?


Thanks in advance.

 

Here's a schematic diagram of your blend-air door system.



Looking up towards the passenger floor outlet on the passenger side footwell, you can see the bottom of the blend-air door actuator.

If you put the key to RUN, engine off, and turn the AC/Heat control panel temp selector back and forth from red to blue, you should see the actuator shaft turn from stop-to-stop. It only turns 90 degrees max travel. If it doesn't turn at all, the motor is probably bad, or the door pivot is broken inside the HVAC Unit housing, locking up the motor.

If it only turns a little or not at all, you can remove the actuator assembly and try to move the door by its shaft. If it won't turn the door is defective, if it will turn freely, the actuator motor is probably bad.

Actuator motors are hard to find. If you're lucky you may find one at a bone yard ('99 to '01 XJ's only).

The actuator motor has an electronic bridge circuit that [I] can't be troubleshot with common meters.

If fuse 25 in the JB is blown the blower won't work.

Check it out and get back.

 

If you cant get good flo thru heater core that would greatly decrease heating capabilities .

 

Excellent! Many thanks!

The motors are available from RockAuto for cheap, so i'm not particularly worried about that.

So far, this sounds all like things i can do without disassembling much, correct? The actuator assembly can be done with the dash still there?

I'll be able to give this a look this weekend, i will definitely report back.


True, but the hoses going in and out both seem hot, which would point to adequate flow. I was going to try a higher pressure flush anyways when i did the radiator job.

This also wouldn't have bearing on the a/c issue as far as i know, and i'm clinging to the hope (and halfway logical thinking, at least i think...) that both my a/c and heating issue are related.

 

Tell us what you find.

 

Late update, been busy with the other cars.

But unfortunately, now, it's winter.

Blend door motor is moving, so that rules out the motor itself and the hvac control panel. Arg.


Looks like my only logical next step is to have this thing professionally flushed. Or maybe the fabled CLR treatment?

 

I have the exact thing happening with mine. I just replaced water pump, t-stat, and flushed my core. Did the CLR treatment, refilled the whole system with water/cascade, and drove it on a 700 mile round trip. Drain, and refilled and my heat is still just not very good. Sometimes it gets pretty warm but others it is luke warm at best even when the temp is at 210.

I did notice the foam insulation in my vents so I am beginning to wonder that I may either have a blend door issue related to the seal around the door or I have some of that foam blocking some of my air passages. I have been thinking about getting an inspection camera and trying to fish it around in there to see what I can find.

 

 

The thing with mine is that the airflow is great, it's just the temperature that sucks.

I have to replace the radiator this weekend anyways, so i'll poke around a bit more before i drop it off to be flushed, but if i can't come to a concrete conclusion by the end of the year, i'm probably going to have to buy another vehicle.

 

Replaced radiator, no more leaks that i can see.

Heat is marginally better, but might be placebo effect.

The bad news is that the air coming through the vents reeks of coolant and the truck IS losing coolant. I'm guessing this means that either:

1) There's another leak i haven't seen in the bay and the air being drawn in is getting the smell

or

2) Heater core is leaking.



Guessing #2 is the unfortunate situation. Thoughts?

 

Heater core blocked recent flush dislogged junk causing leak.

 

Can't say i don't take my time, right?

Heater core is perfect. Flushed it again in daylight, ran perfectly clear, no restriction.

Actuator works fine.

Blend door is broken.


SO, my question to you fine gentlemen today is:

What's the best kit? I see the metal "HeaterTreater" kit, and i see the plastic Dorman kit. Are there others? If i dump another plastic in there, how quickly will it break? Funds are tight right now (We just moved) so the $20 cost of the Dorman kit through Amazon Prime is appealing, but i don't want to replace this thing every month. Every year or two would be ok, but not every month.

Lay it on me.

 

Am i in uncharted territory here? Nobody has just dumped the Dorman kit in?

 

Haven't put in door any repair kits so I'm of no help here.

 

How do you know the Blend-Ar Door is 'broken'?