Was driving my moms 05 silverado and she has duel climate control, we always have it on cold, recirculated air and the snowflake like it on. Worked fine until today, got in to meet her for lunch and the passenger side was blowing cold, but the driver side was like the heater was on, turned truck off then on, went to hot then cold and turned a/c off then back on and it still blew hot. Had lunch with her and let the truck sit for a good half hour while we ate. Got in and the drivers side blew cold as if nothing was wrong. No lights on the dash came on or anything, just wondering if anyone had an answer to why this was happening. Thanks for the input!