HVAC Actuator Recalibration Procedure For GM Trucks and SUVs

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.

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*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.

280 discussions on “HVAC Actuator Recalibration Procedure For GM Trucks and SUVs”

  1. I have a 2007 Suburban LT 1500. The system was blowing cold no matter what the temperature setting. I replaced both the passenger and driver blend door actuators and I manually moved the blend doors prior to installing the actuators to make sure they moved freely. Then I performed the the recalibrate procedure as described in your article. Pulled fuse #38 HVAC/BATT and then started the truck. The HVAC module reset the temp to 74 degrees and I could hear the actuators moving around. I waited the prescribed time and restarted the vehicle per instructions. The system is still blowing cold regardless of temp setting.

    I know for certain the heater core is working as the temperature of the supple and return hoses measures the same temp (165 degrees F). I actually removed the new driver side actuator and help the blend door open with my hand and was able to make hot air come through the ductwork.

    To try to rule out the HVAC module, I tested all the other functions such as the air modes, fan speed and recirculate and they all worked properly. The outside ambient air temperature sensor was reading the correct air temperature.

    I have been unable to find and troubleshooting procedures for the HVAC module.

    Any ideas on how to solve this? Thanks for any insight you can provide.

    1. I would recommend trying the recalibration a few times to see if it will take. Make sure there are no cell phones being charged or anything connected to the DLC. If nothing works someone will need to look at codes and data to see if anything is happening that could impede actuator movement. There is a TSB out stating that the control panel may need reprogramming to correct the issue.

        1. Did you also try doing a recalibration with the Tech2? It should be listed under special functions. Can you move the actuators using bidirectional controls with the Tech2? You will also want to look at command vs actual actuator counts and temperature sensor readings. You will need to look in the HVAC, body and engine data to find all related temperature sensor readings. Not sure if that vehicle uses sunload sensor data but you should also look at that. You might want to try setting the temp control settings to 90 degrees if the system switches to heat it would indicate a faulty interior temp sensor located above the driver’s head.

          1. Thank you for all the great info.
            Yes, I did an actuator door recalibration and it didn’t fix the issue. I was able to move the actuators with the Tech2, however the results are interesting. The driver set when set to “hot” would produce heat through the ducts. The Passenger side would not blow heat on the “hot” setting but it would blow heat when set to “cold” on the Tech2. The temperature sensor readings were interesting as well. The outside ambient air temperature was reporting correctly; the Tech2 and rearview mirror numbers matched. The front inside air temperature sensor said it was 212 degrees F. The rear inside air temperature sensor only showed an * for the value on the Tech2. The auxiliary (rear) HVAC system functions properly for what it’s worth. Also interesting was the ductwork temperature sensors. The ductwork “desired” setting was listed as 35 degrees F despite having the HVAC module set at 90 degrees. The sunload sensors held fairly constant at 225 – 227 for both left and right.

            The inside air temperature sensor reading seems like it’s failed. Would you agree? If the system thinks it’s 212 degrees inside, it’s going to blow cold air, especially when it’s set to Auto.

            Not sure about the rear sensor, but I suppose if I’m going to replace one, I will do both.

            Could a failed inside air temp sensor cause the passenger-side blend door to behave in the opposite manner?

          2. It would seem the interior sensor may be faulty. You could try to disconnect the wiring for it to see if it will allow the system to work better(as a test). If you want to do some further testing, the sensor has a range of -40F to 419F. Disconnecting the sensor harness should induce a nominal temp reading at one extreme or the other. Shorting the two dark green wires (terminals A & D) together should give the opposite reading. Being off a few degrees is generally acceptable. The ignition may need to be cycled off and back on to see a change in the data. If the test shows the two general temp readings it would mean the sensor is faulty. If it has little or no affect on the readings try disconnecting the harness connectors to the left junction/fuse box, inspect for corrosion, loose terminals and reconnect to see if the readings will change.

  2. Any ideas why I cant get my truck to blow out the floor vents? I have a 2007 duramax classic and it goes from defrost to vents fine. When on floor it comes out the dash vents no floor. Maybe the cam is misaligned on the selector?

  3. Hey sparky I have an 01 GMC Yukon xl 1500. I’ve got not hvac ecas fuse. It’s got the 3 dial ac control head. I was gonna try to recalibrate but not sure. I am brand new here so if you want me to start a new ask question thread then let me know.

    1. If you have auto HVAC controls you would need to use the radio fuse instead of the ecas fuse to initiate the recalibration process. If you have manual controls there is no recalibration procedure available according to GM service information. If you need more information, it is much easier to carry on a discussion in the Ask a Question section. To use the “Ask a Question” section of this site to finish the conversation. Locate the “My Account” or “Login” button at the top right of the page if on a desktop or laptop. Within the menu symbol if using a phone. After you are logged in to your account click on the “My Account” button and scroll down until you see the “My Questions” section. Ask your questions there. Thanks, Sparky

  4. Hello, I have a 2013 Chevy Captiva with a Blend Door Actuator issue after a recent battery failure. After getting a new battery, I noticed the AC is always on and all vents are stuck to the front vents. HVAC controls do not change anything. What fuses or steps should I take to recalibrate? The only HVAC fuse I have under the hood is “A/C” and the only fuse under the passenger side cabin is “XM/HVAC/DLC”. Please help!

  5. Is there a way to find out what P/N actuators are supposed to be in which location? I purchased a used truck where the PO had started troubleshooting an issue with HVAC controls and/or actuators and the truck came with a couple extra actuators. I don’t know which ones were pulled and replaced with what.

    1. I might be able to cross reference the numbers if you can supply them. It is much easier to carry on a discussion in the Ask a Question section. To use the “Ask a Question” section of this site to finish the conversation. Locate the “My Account” or “Login” button at the top right of the page if on a desktop or laptop. Within the menu symbol if using a phone. After you are logged in to your account click on the “My Account” button and scroll down until you see the “My Questions” section. Copy and paste your last comment into it as if you were replying and then I will do the same. I want to keep the full discussion in one location so it can help others. Thanks, Sparky

      1. Hi there. I have a 2012 suburban. I’d like to try your procedure. When I look in my fuse box, I do not have a HVAC ECAS fuse. I have the following 3 fuses:

        HVAC IGN
        AUX HBAC IGN
        HBAC BATT

        I was just wondering which fuse I should remove?

        Please let me know

        Thanks a lot
        John

          1. Awesome!
            Thanks a lot, I’ll give it a try.
            I am thinking this will solve the problem I’m having which is: when I turn the temperature dial to the coldest position, the air coming out of the vent is Slightly luke warm…. I think it all started after I changed the battery.

            It’s only noticeable when it’s 95 and humid out. My air conditioner doesn’t work at peak performance even though the system is fully charged!

            I live up north so it’s normally cool up here so it’s usually not an issue!

          1. Hi,

            I have a GMC ’99 JImmy . I could only find one HVAC fuse when looked under the hood fuse box instead of HVAC/ECAD fuse from your solution. Are those two the same thing? Also, the fuse location is a bit different . ( I assume this would be the case depending on year and car model)
            If that is the correct fuse I need to disconnect , is that the only fuse or does additional HVAC fuses ( located to the left of driver side dashboard) needs to be plugged off as well?

            Thanks,
            Jems

          2. The most common issue with those vehicles was lack of mode control and that is all controlled with vacuum. The biggest cause of the problem was rotted vacuum hoses near the canister mounted under the hood on the driver’s side of the engine compartment.

          3. Like you said the most common problems are rotted vaccum lines .. i replaces those with new ones.

            So following up the previous question what fuse should I removed? There is only single HVAC fuse under the hood and it is not labelled as HVAC/ECAD

          4. Okay, the only recalibration procedure is for a system that has auto controls. It only applies to the temperature door actuator. If your vehicle has manual controls a recalibration is not possible or needed.

            If you happen to have auto controls the temperature door recalibration is performed as usual but the fuse will be labeled RDO BATT.

      2. I have a 2004 Yukon Denali XL with ~280,000 miles where the vents would blow out hot air on either the passenger or driver sides when A/C was on. I used your recalibration method and it has pretty much resolved, occasionally I will pull over and stop vehicle and then turn back on and it is resolved.
        Current problem is A/C blowing only out of windshield defrost vents. Does your calibration procedure work for the blend door actuator as well as the temperature actuator? If not, any thoughts or do I just need to take it to get fixed somewhere?
        Thanks for your advice!!

        1. Most likely the mode actuator has failed and should be replaced. The other actuators should also be replaced to fix the problem for good so you don’t have to deal with it again. The problem I have is the mileage of your Yukon. I have been in many of this series of trucks and suvs that have well over 300k and are like new in appearance and performance. On the other hand I have also seen even more that have less than a 150k and are ready for the salvage yard. Replacing a faulty mode actuator with a quality ACDelco part will cost less than $100 and an hour or so of your time, if you do it yourself. If you pay a reputable shop to do the work and guarantee the repair you will be looking in the low $200 to about $300 for the repair. If you were to replace all four with ACDelco parts you would have about $400 in parts and the better part of a weekend of blood and sweat. Paying a shop would be in the $1500 range. So in the end, the condition of your Yukon and your abilities will determine the repair path you should take.

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