Dernz3428

Hey everyone, I just purchased a 2000 Cherokee Sport yesterday. It's been five years since owning my last Jeep(i strayed and got caught up in european sports cars).

Anyways to my issue. I didn't pay attention to the heat when I was on the test drive. Last night I was in the Jeep and with the temp gauge up to temperature I had turned on the heat, but it only blows lukewarm. I wouldn't care typically but i can't defrost my windshield without hot air. I checked the coolant level and it's just fine. any ideas?

Adam_83

Unfortunately I do have an idea!The most common cause of your symptoms is blend-door failure. This is a design flaw created by Chrysler engineers. Basically what happens is that every 20 times the vehicle is started, the A/C system software tells the blend doors to recalibrate to ensure that the airflow is as accurate as possible. The problem is that the stop point is made of cheap plastic. The stop point connected to the actuator breaks. Shortly thereafter, the blend doors break because they cannot withstand the pressure of the actuator pushing them beyond their limits after the stop point has been broken. Passenger side is typically affected first, followed by the driver side. If the doors fall with gravity into the down position, you will maintain A/C. If you hit a bump on the road and they fall into a mixed position, you will have neutral temperature. Either way, no heat is a symptom because that is the up position for Jeep Grand Cherokee (99-2004).

Dernz3428

thank you for the diagnosis. Where might I buy one of these kits to repair the issue?

Macoozie

A million tips to "No Heat" on this forum. Saved my butt many times.

First step, get vehicle to operating temp and feel the heater hoses. Don't squeeze too much, those old brittle heater hoses will rupture in short order.
IF you have hot water flowing through heater core AND your system is FULL, then search for lots of other steps.

If the heater hoses feel very different in temp, fluid is low or core is plugged.

After vehicle cools off, remove both heater hoses from front of engine, and blow out the junk. No Air Compressor? Use your mouth or gently use a bicycle pump connected to the return hose with the source hose pointing down (towards the starter). This nasty junk stains, so not on concrete driveways!

Dernz3428

I checked out the blend-door and it seems to be fine. I read on a site that sells them how to diagnose whether or not it was broken.

I also cleaned out the hoses to the heater core as mentioned above.

I have better heat than i did before, but its not super hot like i'd expect to be blowing out. I think i'm going to change the thermostat just because it's a simple cheap start to fixing the problem

Tom Cin

I have an 89 and just resolved the heat issue by removing the hoses and adding a female garden hose end on each flushing both sides a few times this cleared a load of crap out and the heat working fine.

BRiker10

This worked great form my 2000 Cherokee today, HUGE difference.

98jeepcher

^x2 This worked for me.

hghgrad

I'm going to have to try that on mine tomorrow.

wherestheslide

I'll be trying this also. Not sure if it's better to run water through for a few minutes, but it's 30 degrees and my garden hose will not even unravel.

pikapp504

YouTube is blocked here @ work, but if it's the Eric The Car Guy video, then I did this as well and my heat is amazing now! Flush the heater core both directions about 5x, pour in a 50/50 mix of CLR/water, let it sit for 5-10 minutes, flush it both ways a few times again (use compressed air too if you can) till clear, fill with full strength CLR for 2-3 minutes, flush both ways with water and compressed air till clear water comes up, reattach hoses, top off coolant w/ 50/50 mix...and you're done!

wherestheslide

Yup, that was Eric the Car Guy. Luckily I have a decent air compressor with a tapered nozzle, so hopefully no ethylene glycol bath ahead.

todcourt2

I had this problem with my 2000 grand cherokee, turned out to be what they call a flapper door inside the dash. Ran about $800 to replace. Thank God for extended warrenties!

wherestheslide

Blew out a bunch of liquidy crud from the heater core using an air compressor. I have not topped it off yet but it seems to be acting better with luke warm heat this AM.

I saw a video on replacing the blend door (another vehicle I believe) and that will not be happening anytime soon for me. I'll get a cigarette lighter heat blanket before I yank the dash.

Dernz3428

i also had a good amount of crud come out of mine when I cleaned it out and have better heat than i did, but i feel that it should still be hotter than it is currently coming out. I just deal with it and have gotten used to always having it set to blow as hot as possible on the dial.

as for the blend door project it's not something that requires the dash to actually be taken out. if you choose to go in from the top as they would at the dealer then yeah the dash needs to be dismantled, but after I had read through the links and things people on here directed me to I found the main alternative. I read about the metal blend door you can order and install from the passenger footwell with the use of a Dremel(sp?) tool. Seemed to take about 20-30 minutes at most. Only reason I didn't go ahead and just replace it then post the photos of the project on here is because the new metal blend door is kind of pricey considering mine is still in good working order.