Originally Posted by debbie9339
Jeep Grand Cherokee 1999 - my heater is not blowing any warm air at all. Can someone direct me to what might be wrong....it was working two weeks ago and just stopped sometime in the last few days. Debbie
First thing to do, before you go out and buy the blend door, is to recalibrate the HVAC blend doors.
The procedure is:
Calibrating AZC door actuators
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. (The PDC is the long box, near your battery, with a lid the swings up. The IOD fuse is fuse 15) http://www.wjjeeps.com/misc/power_dist_ctr_02.jpg
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.
Every 20 key cycles the AZC head initiates a re-calibration routine which identifies pulse counts required to achieve full door travel. Also during this routine all modes and functions are validated as functional. When the self calibration routine is complete, the control head resets itself to its last settings.
The air conditioning compressor will engage in certain modes to cool and remove moisture from air entering the passenger compartment. The AZC control, when it is not set in the auto mode, always defaults to A/C enabled. The LED illuminates when the control requests A/C. The customer must toggle A/C off by depressing the button every time he turns to manual mode or the A/C is enabled. Additionally, when the vehicle is off for a "calibratable" amount of time, automatic A/C is again enabled and the customer must again force it off by depressing the button.
I have had the problem of my HVAC blowing hot air in the summer, three times in one month. I already have new blend doors.
This may save you money, if it is the problem.
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