Power Door Lock Actuator Going Out

[ScottyBoy]

I have a strange problem. The drivers door power lock actuator seems to be going out. But now here's the strange part. It will work fine if the temperature outside is around 40 degrees or warmer. But if it gets any colder than that it will stop working. Its annoying because several times I've gone to work on it when it warmed up outside and found it working. This is how I finally made the connection with it not working when its cold, but working fine when its warmer. I would under stand the lock freezing up if the temp was below 32, but it will quit working around 40 degrees or so. Can I just assume that I have a bad actuator? Also, my truck is still covered by an extended warranty, but when I went to go have it fixed it decided to work. They told me if its not acting up when they see it, they can't fix it. What should I do?