I need some help with the HVAC on a 02 Grand Cherokee with ATZ controls. I bit the bullet a couple of weeks ago and pulled the dash because my recirc door was broken and I thought my blend door on the passenger side was broken also. It turned out it wasn’t, it had a bad actuator, but I already had the blend door replacement from Jeep so I went ahead and replaced it with the new metal door and replaced the driver side along with the recirc door, which by the way wasn’t there at all. It had been removed but the cage was there. Go figure. Anyway, I put the HVAC unit back together after cleaning it up and I checked that the blend doors moved freely before I put the actuators back on. I reinstalled it in and the dash and everything worked fine. A few days ago, the passenger side starts blowing hot air. I checked for errors and there is a code 56, Right side blend door travel too far. So I thought, well, I’ll recalibrate the doors and see what happens. After I did that, the door starts working again and the code 56 is gone. A couple of days later, hot air on the passenger side again and code 56. I recalibrated again and it’s working again for a couple of days then code 56 and hot air again. So now I’m confused as what to do. I need some opinions here. Bad actuator or bad controller? Is there a way to test either? Also, the air flow on the passenger side is rather low. I don’t know if that is related or not. Help!
Update 8/11/10: It was the controller. I found a used one at a salvage yard for $20 and installed it. All has been well for a few weeks now. No more error codes.