Ranger and Turbojimmy are right, on my 98 Deville, I also got hot and cold at the same time, the actuator for the passenger side is on top as you know, the drivers in on the bottom as Ranger as said. You need to have the passenger control turned off and then pull the hush panel and then look at the rod as it moves. What may be happening is the rod is moving ok, but then continuing on as the temp button is being pushed for the warmer. this would result in the temp going back to cold again. You could try taking the rod off and then pushing it manually to close the door, this would be only a quick fix until you are able to acertain excactly the problem. The actuator is about 80 dollars and the passenger side was a real pain to replace (big hands), but the drivers should be a lot easier. The shop manual does also mention that the controller itself may have to be changed. Hopefully that does not mean you. For mine I had to plug my Tech2 in and look at the counts as I commanded the doors, lucky for me it was only the Actuator motor and not the programmer. Goodluck and hope you find the heat