Hi TomTom51.. you do have to disconnect a couple things to get that cabin air filter out, so its very possible that one of them didnt get plugged back in. I would start there. just ask the shop that did it real nicely: "hey, any chance something didnt get plugged back in?"
These are the steps that alldata outlines:
1. Disconnect the negative battery cable.
2. Remove the passenger junction box (PJB and PJB bracket). See: Maintenance\Fuses and Circuit Breakers\Relay 3. Box\Service and Repair
4. Remove the side wall.
5. Disconnect the evaporator temperature sensor connector.
6. Disconnect the power MOS FET connector. (Full-auto air conditioner)
Good luck