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p3vinny 07-19-2013 12:22 PM

Passenger AC not blowing cold 04 Limited
Hi all,
I recently replaced my blend doors with OE replacements, on my 2004 Limited (Dual AZC). Everything seemed to be working fine until the really hot weather kicked in. Now, the passenger ac vents only blow lukewarm air when it is really hot (above 95 or so).

The doors seem to function, i.e. air temperature in each zone changes with respect to the set knob, it just doesn't get as cold on the passenger side. I also occasionally get codes 20 22 24 or 52 54 56 (l/r and recirc door travel too large) I can clear the codes and have tried recalibrating several times.

I'm hoping to avoid removing the dash again, but I suspect that is where I'm headed. Anybody have any experience with similar symptoms? Thanks in advance!


Frango100 07-19-2013 02:48 PM

Re: Passenger AC not blowing cold 04 Limited
You say that luke warm air comes from the passengers side vents, but does cold air come from the drivers side?
You could control the passengers side door without using the automatic control function: while already in the test mode turn the left temp selector until pointer number 41 appears (right temperature control actuator), press the AC button again and the right display will show the actual actuator position. Now by turning the right temperature control knob you can manually operate the right blend door. Check if you can get cold air out of it this way.

p3vinny 07-19-2013 04:52 PM

Re: Passenger AC not blowing cold 04 Limited
Thanks for the reply! The driver's side is blowing cold air, and seems to operate normally in all regards. When the temperature setting knob is increased on the passenger side, the air temperature increases accordingly. Conversely, when decreasing, the temperature decreases, only not as much as the driver's side.

I did some more troubleshooting based on your reply and found the following with both left and right temp knobs on Lo.

Pointer Number 31 (Current temp position <in counts>): 0
Pointer Number 32 (Temp target position <in ratio>): 0

Pointer Number 41 (Current temp position <in counts>): 1060
Pointer Number 42 (Temp target position <in ratio>): 0

If I adjust the target position (Pointer number 42) to 255 which is the highest value the air temp increases to what feels like full heat (same as the left side). As I decrease the target position toward zero, the temperature decreases. If I increase toward 255 in pointer number 42 and then switch to Pointer 41, the value decreases rapidly toward 1060 +/-.

The conclusion that I am drawing from all this is that something is preventing the blend door from moving to full cold position. I don't see any way of verifying this without pulling the dash again and opening up the HVAC unit.

Frango100 07-19-2013 06:11 PM

Re: Passenger AC not blowing cold 04 Limited
Yeh, unfortunately seems that something is preventing the full travel of the blend door.
Is 1060 the lowest position pointer 41 will reach?

p3vinny 07-19-2013 08:10 PM

Re: Passenger AC not blowing cold 04 Limited

Thanks for the help... yes, it seems like 1060 is lowest.. +/- a few points. I'm not really interested in cutting a hole in the HVAC box, and that's the only other way I can think of to see what's going on in there without pulling the dash.

Not sure when I'm gonna pull the dash. It's still too soon since the last time...

Thanks again!


Frango100 07-19-2013 11:14 PM

Re: Passenger AC not blowing cold 04 Limited
Hi Phil.
Are you sure the calibration was done in the right way? I see that you did your homework and know a lot about the AZC system already, but just to be sure that you don't tear your dash out again without reason.
After you do the calibration, do you see different values for pointer 41?
I would expect a pointer 41 value of 0 after the calibration, eventhough the blend door is maybe not completely closed.
Was the engine running and AC compressor switched on when you where moving the right blend door in actuator test mode and how was the air coming out of the passengers vent? Because it could be that now with the door completely closed you get the pointer value of 1060, but when its in autocontrol that it just goes until 0 (and won't be completely closed). (does it make sense what i'm saying, its a bit late overhere already and maybe just telling some BS)

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. 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.

p3vinny 07-20-2013 01:07 AM

Re: Passenger AC not blowing cold 04 Limited
Thanks again for the info. I calibrated it the same way as you describe, except I pulled the battery cable rather than the IOD fuse. I hadn't checked the door values right after a calibration. I'll try that next to see if it is indicating something different.
I'm not too optimistic though, since a sticky door could explain the symptoms.

Thanks again!


Frango100 07-20-2013 01:52 AM

Re: Passenger AC not blowing cold 04 Limited
I'm not sure if disconnecting the battery has the same effect as pulling the IOD fuse.
Pulling the IOD fuse will not remove all power from the jeep, certain functions will still be under power with this fuse out, which could be necessary to make the calibration work.
With ignition in on, which is necessary to do the calibration, the AZC is fed by fuse 15 (IOD) in the PDC, but also by fuse 20 on the JB. By removing the IOD fuse, there is still power via fuse 20 to the AZC, which can be a requirement to start the calibration. I would give that a try.

p3vinny 07-20-2013 12:10 PM

Re: Passenger AC not blowing cold 04 Limited
Good point on the IOD fuse. I was just pulling the battery cable since it was easier and I had been doing multiple re-calibrations while troubleshooting. The re-calibration appears to work when doing it that way, but.... I'll give it a shot pulling the IOD fuse!

Thanks again,

p3vinny 09-25-2013 03:16 PM

Re: Passenger AC not blowing cold 04 Limited
Update on my HVAC saga...

Finally pulled the dash again and pulled the HVAC unit. Both blend doors both seem to travel unrestricted in the housing. I bench tested both actuators and they seem to work fine. When I reinstall the actuators and apply voltage they work, except they will continue to travel beyond the stops.
The doors remain where they need to, but the linkage between the actuator and the door stretches. When it is doing so it makes a 'clicking' noise as the actuator strains to continue its travel. I also have heard this same noise consistently after engine shutdown (prior to pulling the dash).
This is a new wrinkle, as it seems the actuators do not shutdown when reaching the door stop as expected. It also does not explain why the passenger blend door did not reach full cold position. I will keep troubleshooting and post if I find a solution...anybody with ideas on how to proceed? Thanks in advance!


Frango100 09-25-2013 08:44 PM

Re: Passenger AC not blowing cold 04 Limited
Hi Phil,
I don't understand how the actuator can continue rotating when the stop is reached. The blend door actuators are mounted directy to the blend doors, so when the stop is reached, the actuator should stop and the then higher current should be a signal to the AC control head to switch of the power supply to the actuator.

p3vinny 09-25-2013 09:50 PM

Re: Passenger AC not blowing cold 04 Limited
Those are my thoughts as well. When I had the HVAC on the bench I applied power and watched the actuators... the linkage (plastic collar that slips over the door assembly hinge) actually seems like it deforms slightly allowing it to continue to spin - the door assembly remains on the stop. I'm guessing higher load voltage is not 'high' enough to stop the actuator motor. I tried switching motors with the recirc door, same result.

I am going to swap out the actuators with new ones and see if that works.

Thanks again!


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