[Mikeg175]

Ok , I searched the threads and found some close posts, but this was a little different to most of them . Here's the problem 2002 Limited 4.7 , all of a sudden today I have no heat . Well that's not true , it will blow hot as he!! when I turn the heat to HI . When in high it will blast heat from everywhere . I did the Blen dor fix about 2 weeks ago along with the recirc door treatment . The heat worked fine till today , it will blow cold when I turn it down to where the ac comes on , the fans speed up and it blows cold , when I turn it up to 85 it blows cool, not cold air , then one click to HI and it blasts heat . When I did a code search , I got 47 52 54 56 , but I don't think I reset it after the blen dor treatment , because everything worked like a charm . After my searches I was going to check the connector behind the glove box , but in the searched it said nothing about having heat when on HI , so not sure that would be the problem . Thanks for any input .

[cmonson]

you have to calibrate the blend doors. I can guarantee that is your issue.

[cmonson]

Calibrate the door actuators after making any repairs to the AZC system. To calibrate the door actuators proceed as follows:

1. Turn the ignition on.
2. Set the AZC to automatic.
3. Turn the ignition off.
4. Remove the IOD fuse from the Power Distribution Center. Wait several seconds, and then install the IOD fuse.
5. Turn the ignition on. Do not touch any of the AZC controls for at least one minute to allow the calibration function to run to completion

[Mikeg175]

Ok , I did this , and it worked for like 4 mins , then back to same as stated in first post . I removed negative battery cable though , I would think it would be the same thing , but not sure . I was looking for the IOD fuse , wasn't listed in my manual and said F-it just pop the cable off . Will the IOD give a different response ?

[Mikeg175]

Ok , I ran back out , found the IOD fuse , did the calibration . Still the same , what it seems like , is that the temperature sensor is reading it wrong or something . I can hear it moving all the parts behind the vents , it actually moves them a lot . Is there a way to check the temp sensor ? I still get codes 52 and 56 , but when I checked ( its easy now with the blen dor fix hehe , already cut open ) its working fine . I checked all my fluid levels was thinking maybe its fluids , but it's not . I also have this weird thing happening when I check for codes , sometimes it pulls up numbers , which I can adjust from 1-89 . will this affect me , I was thinking maybe that needed to be on the temperature , so I left the windows open and put it on 59 , which is what temp was reading . Does that do anything , I have tried it on 1 and on 89, doesnt seem to do anything at all .

[Mikeg175]

Looking a few other posts all over the net , could this be a clogged heater core ?

[ratmonkey]

not likely, the heater core does not have any way to vary the fluid going to it based upon your choices at the temp controls. it's hot all the time or not hot all the time when plugged. you won't have a cold, cold, cold, hot as heck deal going on.

if it works correctly for a few minutes or however long after recalibration, i'll say your repair isn't up to par and you left something loose. or your motors went and the cheap fix won't take care of it.

[Mikeg175]

I guess , Ill tear it apart and recheck it all . Thanks

[redhatman]

Something is probably sticking on the Temperature Blend Doors. WJ's are horrible with the Blend door problem. You said you were getting real good heat at a certain setting, so that rules out quite a few things. The heater core being one of them.

[cmonson]

I believe there is a TSB for your issue.

check this out.

http://www.wjjeeps.com/tsb/tsb_wj_241699.pdf

[Mikeg175]

I wonder if I can still get this done , even if Im way out of warranty ?