Q: My actuator works backwards

Hello. We will need to observe several other factors in order to pinpoint what the issue is. When you say you are turning on the vents, what setting are you turning on when this happens? Is it all temperature settings that turn on defrost? This may help us determine if this is a blend door issue, switch issue, or other electrical issue.

It’s common procedure that the air condition system be turned on when the system is set to defrost to help dehumidify the air. If this is what is happening, and an unusual amount of cold air is being blown through the vents, you may be experiencing a blend door issue.

If it doesn’t matter what setting you are trying to run, the issue is very likely a switch or wiring problem. You will want to have the wiring inspected for a short somewhere that is giving the other components power when it should be. While testing the switch may be a little harder, but can be done. Keep in mind with the time it takes a technician to diagnose the switch, you may have been able to pay for a new switch to be installed.