The topic of how to perform the actuator recalibration procedure on Chevrolet , GMC and Cadillac Trucks and SUVs has become an ever increasing topic of discussion.
For manual systems it does not matter where the a/c controls are set but if you feel the need to do something, turn the blower switch on (I prefer speed 3) and set the temperature sliders about .5″ to .75″ from full cold.
For auto systems, press the auto button, with the key on.
Turn the ignition off.
Remove the HVAC/ECAS , 10 amp fuse in the underhood fuse box* or disconnect the battery for one minute.
*Fuse locations can vary from year to year and between different models. Hopefully I will be able to build a list for this.
Install the HVAC fuse or reconnect the battery.
Start the engine. On systems with auto a/c controls the controls will default to 74 degrees F when the ignition is turned back on.
DO NOT TOUCH the a/c controls.
Let the engine run for 1-2 minutes.
Turn the ignition off for at least 10 seconds but no more than 30 seconds.
Restart the engine and then test the a/c controls.
Hi Sparky. I’ve been battling this issue for a year now. I have a 2000 Pontiac Grand Prix GTP with electronic dual climate. The issue is on the driver side vents stuck on cold. I replaced the driver side actuator and no improvement. I reset the system by disconnecting battery. I think the reset process is working because it seems that when you key on the car for the first minute or so, the HVAC does its own thing and you can’t control it until its done. That didn’t work, so i did the reset again. Then I unmounted the actuator to see if it would even spin when I turned the dial. It doesn’t move at all. I have NEVER got any trouble codes, even with the original one, so I unplugged it all together and then got the flashing passenger side icon indicating an error present. I plugged it back in, unplugged the battery and did the reset again with the actuator still unmounted. still not seeing it spin at all. My thought is that I need to see the actuator spin or do something before I mount it again. I tried plugging back in the original one, unplugged the battery, sat through the re-learn and nothing. no error codes with the original but it still does not spin. I tried leaving the battery disconnected over night, plugged in the new actuator, and fired it up the next morning and still.. nothing. no spin. no error code. What am I missing here? Seems the HVAC is capable of detecting when an actuator is not present, but I’m not getting this thing to work, whether its mounted or not. Passenger side has no issues, hot and cold work great. When I turn the gear to move the blend door, it spins and I can make the air hot.. but over time it goes back to cold all on its own with no actuator attached to it. Whats my next move?
I would start by verifying that the replacement actuator is the correct part number for the application. The correct ACDelco part number for your vehicle with auto HVAC controls would be a 15-72971.
I removed the “AC “fuse in engine compartment ( there is no fuse labeled HVAC/ECAS) but AC did not come on following calibration procedure above.
I can disconnect battery and AC will come on for few trips. When I do this I just leave ignition key on for couple of minutes. Do you think it would make difference if I actually ran engine for couple of minutes as you suggest. It is also strange that disconnecting battery resets AC for a while but pulling fuse does not
I don’t know what kind of vehicle you have so I am at a disadvantage. However in most modern vehicles an underhood a/c fuse is for control of the compressor only. There is another one for battery supply to the HVAC control panel which is the one that would need to be removed. I suspect that you may have an Trailblazer or Envoy and the correct fuse would be the HVAC B fuse in the rear fuse box.
I have a 99 Silverado 1500 I cannot find an hvac/Ecas 10 fuse under hood I only find front hvac and rear hvac fuses but 30 amps is it in the in cab fuse box?
Your truck does not use a recalibration procedure and does not have that fuse.
Hi thank you for this post! I did it on my 2004 Yukon Denali XL. I wanted to note that when I performed this procedure I also removed the RR HVAC fuse as well. Some Yukons, and Tahoes have 2 systems so I figured I would pull both fuses. Hope this helps! Thanks Sparky keep the tips flowing.
I just think tried this recalibration procedure for my 2005 Yukon.
Now my driver side vents are blowing hot at all temp ranges
what could I have done wrong
I would recommend trying it again and make sure you follow the instruction fully. More than likely the driver’s temperature door actuator has failed or is failing. The recalibration procedure has just found it.
Thanks for your answer. I left the truck alone for about an hour after performing the above procedure. When I drove it later I’d found to my surprise that everything was working correctly, and much better meaning the original issue, weak coolish air flow through the passenger vents had corrected itself. Now I have great cold flow through all vents. So maybe it took a while for the computer controlled actuators to update? Either way, its working and I appreciate your help.
Dave
Glad that it is working for you. It may work for a long time but I would get prepared to replace the actuators.
The blend door actuator was replaced, but I don’t think they re calibrated. Based on the fact that its now working I’d say that was a pretty fair bet.
Dave
Question, I have a 2004 Yukon Denali. I had the issue where going down the road with the AC on, the heat would sudenly come on. I had a shop change that actuator which worked fine. Recently I noticed an issue that the passenger side dash vents blew coolish, but nowhere near as cold as the middle and driver side vent. I thought it might need re calibration so I followed the above procedure and now, I get cold air from the defrost vents and the floor, but nothing from the dash. I figured I missed a step and so I repeated the procedure – still have nothing from the vents in dash at all.
Thanks!
Depending on which method you started with you may want to change. Disconnect the battery rather than remove the fuse or vice versa. Having a scan tool is the best way to tackle the situation but most people do not have access to a proper scan tool for this system. If a few more tries at recalibration do not work I would suggest that the mode actuator is faulty and will need to be replaced. Something that you may be able to do is have someone help you initiate the recalibration while you physically observe the movement of the mode actuator. There are also tests that can be done at the actuator connector to get a better grip[ on what is going on. Frankly it is easier to just replace the actuator rather than trying to test without a scan tool.
I did remove HVAC B fuse from my 2008 Trailblzer and AC did not reset. So I followed procedure by removing battery cable and it resets for a few local trips and then Temperature gauge goes to zero and AC shuts off. Do you think if I replaced driver side actuator this would solve problem? I personally do not think so as I can not see any connection between blend door and temperature gauge.
If you think this would help do you have instructions to replace actuator for driver side dashboard vents?
The compressor not turning on and the temperature gauge going to cold has nothing to do with a recalibration. Instead there is a code setting in the PCM which makes the PCM decide to turn those two items off. I believe I answered this question for you yesterday. Check your account and look at the question you asked and my answer.
You referred to codes 125 and 128 which you said recal procedure will not fix AC and Temperature going off . So what is solution? You mentioned PCM
Also can bad actuator cause AC and Temperature gauge to go off
Thanks for your help
P0125 or P0128 are codes related to a a faulty engine thermostat. The PCM sees the engine not warming up properly and errs on the side of caution and turns the a/c off. It also turns the temperature gauge off to get the driver’s attention that something is wrong and you need to fix it. Disconnecting the battery clears the PCM codes and therefore temporarily restores the compressor and gauge operation until the code sets again. A faulty actuator absolutely cannot cause the compressor and temperature gauge issues. As stated earlier have the engine codes checked and proceed based on the codes retrieved.
I have a 2004 Yukon Denali as well. I tried this even though my system is fine. I did notice it recalibrate the actuators I could hear them adjusting a few times. Thanks I will keep this in mind had no idea.
Thanks Sparky!!!!