Hi everyone, I have been looking through all the threads for info on heater problems on Cherokees equipped with the dual temperature controls. (I have heat on the drivers side but not on the passenger side) Dealer says it is a control head problem, I am thinking blend air door problem. Codes on dash panel are 54 and 56. I have found 54 is somehow related to travel distance of the blend air door. Does anyone know what a 56 is? Thanks in advance.

54 is left temp door travel too large and 56 is right temp door travel too large.Who said its a control head ,a Toyota dealer?The blend doors in the heater case are notorious for breaking.Thats why you get those codes and no heat.Chrysler came out with updated parts because this is such a problem.

Thanks xj31!. This was a Jeep/Chrysler dealership that told me it was the control head. They said a new TCH would be $425 and a couple hundred to install and suggested I check around at a couple of junkyards and find one. They then could install and calibrate the used one. After reading several posts on this here in this forum, I am convinced it is a broken blend door just as you stated. I am not looking forward to dismantling the passenger side dash area to resolve this as well as pulling the heater core but it looks like there are no other options for replacing the passenger blend door.
I live in Michigan and even with the heat on the drivers side working, my wife is not too keen to sit and have cold air blow on her everytime we go somewhere. Any suggestions for getting through this repair myself would be greatly appreciated. Thanks again.

I'm surprised that a Jeep dealer would seem to not know about the blend door problem.I work at a decent size Jeep dealer and we replace those doors a lot.We see at least 2 or 3 a week if not more.The control heads do go bad once in a while but it's not that common.Your dealer should know about a bulletin on those doors it's 21-001-04 and it gives new part numbers for all the doors.They come in a sub-assembly.It's a small section of the heater case with the 2 blend doors installed.They seem to be a little sturdier than the original ones.There's different part numbers for different years but for a 99 the blend door number is 5134349aa for the AZC system.List price on that is about $125.00.As far as doing it yourself,I don't know your skill level,but it isn't a job for a beginner.You have to pull the dash and you have to evacuate the AC.If you're gonna try it yourself,let me know and I will try to give you some advice on the easiest way to do it.

Thanks, I plan on removing the dash sections as far as I can and still leave the thing driveable. I'll then have the AC taken care of at a local garage and then continue with replacing the blend door. When I get that done I'll have the AC recharged. Any advice would be great! I'll probably take some digital photos along the way to aid in the reassembly and will separate and label all parts as I go. I am concerned about passenger side air bag so would like to disable it before starting if possible. Thanks again.

OK, for anybody who is interested, on Thursday I took the Jeep in and had the AC evacuated at the local Firestone shop. ($70) On Friday, I had to drive an hour to get the replacement part referenced in the thread above as the 2 "local" Jeep dealers did not have one in stock. ($125) Friday afternoon I started in on the interior dash/console and worked about 5 hours. Picked back up Saturday. Getting the heater hoses off on the engine side of the firewall was probably the worst part of the job. No room at all. Removed entire duct system onto the bench and dismantled it. Sure enough, the hinge on one of the blend dodrs was all boogered up. Servo motor probably was trying to activate it but the shaft was just spinning in the hinge. Put in the new one, checked all the servo motors while I had it apart and started reassembly. During teardown, a roll of masking tape and a felt tip is a good idea.Worked maybe 6 hours Saturday. Worked another 3 of so hours on Sunday to finish up. Only real bonehead lay on my part was not pushing the glovebox light connector onto the wiring harness before hogging down the dash cap. Screw it! Jeep is back at Firestone today for AC recharge. Firestone only charged labor for the evac and will only charge for the freon today. Heat working great on both sides. Did have about 10 fasteners leftover. Probably develope some squeaks down the road. Total repair cost about $250 vs. $1000 at a shop. Took =/- 15 hours. Thanks to all in this forum for their help. Stupid dealer would have had me spend $625 to replace something that had nothing wrong with it.