Since purchase, one or more of the AC actuators has thrown trouble codes and after three years, all but one had thrown a code at least once! After much research, years, I nailed down which GM and ACDelco part numbers were for each position, or so I thought! The most troublesome actuator was the driver's temperature control so I bought a GM 89018375 which also had ACDelco's number on the box, 15-72972. This one was made in Mexico by S&G Group. My youngest daughter took on the task of replacing this one for me and swapped it out. We fired up the truck and Tech-2 and did a calibration, air was blowing hot when it should have been cold, always did the opposite unless manually commanded with the Tech-2. After a couple of relearns, even the passenger side temperature actuator started acting up! She put the old one back in for me and I started googling. Like we did for the window switches, we came across a company on Ebay claiming to sell the same actuators that shipped with our trucks from the factory in white boxes without the GM stickers, from the same company that made them for GM. I sent them an offer, they accepted, and a few days later the new one showed up. This one was made by CEI, same as the one we pulled out, and is part number 89018365 or 15-72971. THIS is the right actuator for the driver and passenger temperature controls! My little one installed this new one for me, we did the calibration and now none of the others are throwing codes either! All seem happy at the moment! Knowing that we had so many previous codes, I ordered another at the same price. So this is what I know about actuators; so far: GMT900 Auto AC 89018374 - 15-73952 = Mode Actuator (Trouble Code B3779) - Driver's Footwell. 89018365 - 15-72971 = Temperature Actuator, Driver's Side (Trouble Code B0413) - Passenger's Footwell. 89018365 - 15-72971 = Temperature Actuator, Passenger Side (Trouble Code B0423) - Behind Glovebox. Not going to speculate on the others until I see them! LOL She then did a great job washing the truck, what a kid! Only cost a t-shirt and hoodie from Bass Pro Shops and ice cream; so far!