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.
My late 08 GMC Sierra HD air delivery is hot and suspected blend door needs calibration, have done it a couple of times without success. Fuse is HVAV Batt that I removed not the HVAC Ign fuse. Any help would be appreciated.
The blend/temperature door actuator has likely failed and needs to be replaced.
Thanks for the info.
I have since accessed both the upper and lower actuator and can feel them rotating if I put light finger pressure on the shaft and change the temperature setting up and down.
This has been a problem I have been putting up with for a while but times like now (Middle of summer here in Australia) when temperatures get over 40c and the vents are blowing hot air. I have had the AC checked but it is no match for the heater core. Thinking of bypassing the heater core but would rather fix it correctly.
Any suggestions please. Cheers Brett
Start by checking the a/c lines at the firewall after the a/c has been on for about 5 to 10 minutes. Both lines should be cold and nearly the same temperature. If they are remove the driver’s side temperature door actuator and rotate the door shaft with your fingers to the full cold position. You should be able to feel the door stop at the end of it’s travel. Then feel the vent air on the driver’s side vents to see if the air now feels cold. I said driver’s side but since you mention you are in Australia the passenger side might be easier to check.
hi I have 2003 Chevy Silverado and my trucks ac works fine but my heater only works sometimes. also the vent on the right barely blows but can deal with that. also the two knobs when I turn them up, the numbers will glitch and keep going down it can take a minute to get the temp up on both of them. anyway I started my truck cut on my heater hit the auto button then shut the truck off. popped my hood pulled the fuse for a minute and a few seconds. pushed it back in started my truck and the auto was on. but they were still set at 90 so it didn’t change them to 74. I let it run 2 minutes anyway then shut the truck off and went 15 seconds. started it back up. anyway hoping maybe you know what is bad and what I need to do next. I hope I gave enough details so you can help. thank you for your time
I meant the left driver side vent doesn’t blow right not the right side. the roght side both of them blow air. but like I said the heater only works sometimes sorry would had edited my post but couldn’t thanks
You need to make sure you pulled the correct fuse because anytime battery power is removed from the HVAC module and then reconnected the display will default to 74 degrees. You may need to disconnect the battery or remove the control head and disconnect it to be sure power is removed.
well pulled the battery’s power like you said and everything went right. but didn’t make my heater blow hot again so guess I need a new Actuator. witch one do you think is the problem? think they is like a total of 4 of the right.
I would start by checking the engine coolant level first. The heater core is the first thing to empty out if the coolant level starts to drop. There are two temperature door actuators and it varies as to where they are located so I would need to know the details of your vehicle.
Ok. I have been reading and reading I can’t find an answer.
I have a 2010 chevy traverse.
It is not manual air controls.
The mechanic believes my actuator has gone bad. I am getting only hot air on the driver side and cold air on the passenger side.
Now here’s the kicker. Something similar happened about a year ago.
Both times I took my car in for unrelated work with my A/C working. When I started my car the air was off so I turned it on and started adjusting it. It starts blowing hot air on the driver side. Both times this happened they had to move my fuses to get to other areas. This time is was the front motor mount (completely unrelated).
I think something about moving the fuses is causing my issue. I don’t think I need a new actuator. I’ve heard no noises and had no issues until they pulled the fuses.
Plus I had the actuator replaced last time this happened. About a year and a half ago.
I have tried locating the hvac/ecas 10amp fuse and I don’t see one labeled that. The only hvac ones I see are more than 10amps.
I hope you can help. I would love to be able to do the reset and see if it works.
You will need to remove the HVAC fuse in the interior fuse box to perform the recalibration.
Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.
(w/o Scan Tool)
•Place the ignition switch to the OFF position.
•Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
•Install the HVAC/ECAS fuse.
•Start the vehicle.
•Wait 40 seconds for the HVAC control module to self-calibrate.
•Turn the ignition off for at least ten seconds but no more than thirty seconds.
*Start the engine and test the system.
So would it be worth trying a second time if it didn’t work? Or just figure the actuator is broken and needs to be repaced? That was infuriating trying to get the fuse in and out. There is a bump in the car, just under the box, that made it nearly impossible to get it back in. But it’s possible I left the car off for more than 30 seconds after the initial turn on with the fuse replaced.
I would certainly try a recalibration a few times before giving in to replacing the actuator. Especially since you stated this has happened in the past and that a recalibration fixed the problem then.
I have a 2005 Avalanche that has 2 issues. 1st, the driver side blows hot all the time (passenger side works fine – very cold). 2nd, no matter where I set the control it blows out the defrost. The drivers side hot air issue has been coming and going for about a year but seems to have finally given up and just blows cold. I bought two actuators from advanced auto. Replaced the drivers side blend door actuator and it did not help that issue. Tried the recalibration twice and it did not help. As for the second issue, I can’t get a socket on the top bolt. Gave up for now. unplugged both actuators and set the positions by hand. I have great, cold AC but eventually may need heat or defrost. Any help would be appreciated.
Go to the passenger side of the dash and remove, inspect and re install the harness connectors. Look for signs of loose terminals or corrosion. Repair any problems found and perform the recalibration procedure. If the problem persists create a free account and ask your questions in the Ask A Question section. Thanks, Sparky
I have 2008 gmc acadia nothing is working to get my driver side blower to stop blowing hot did the recalibration bought a new actuator. And its still stuck on hot i can flip the switch with my finger i get cold air but as soon as i plug the acuater in in goes right to hot
More than likely you will need a compatible scan tool to diagnose this problem. If you want to try and pursue this without a scan tool I would be glad to add some assistance but understand that testing without a scan tool to back up the data can cause a misdiagnosis? We really need to see what the computers are seeing and attempting to do.
You will need to open a question and answer session in order for me to provide more assistance.
Here is the the operating principles behind how these actuator are controlled.
The actuators operate using 5 circuits. A 5-volt reference, low reference, signal circuit and two bi–directional 0 or 12 volt control circuits. The HVAC control module supplies a low reference and 5-volt reference to the potentiometer. The HVAC control module monitors the voltage drop across the potentiometer on the door position signal circuit. As the actuator door changes position the door position signal circuit voltage also changes. The two bi–directional control circuits enable the actuator to operate. Both circuits are set to 0 volts when the HVAC control module detects, from the feedback potentiometer, that the actuator is in the desired position. In order to move the actuator, the HVAC control module switches the appropriate control circuit to 12 volts.