Cruise control Set function problems - 2002 Quest

[abehil]

I have a 2002 Quest with a cruise control issue. I'd like some advice on troubleshooting to find the actual cause.

Set button is intermittent:
When I press the cruise control it always turns on normally. But to set the speed I might have to press the set button several time before the set light comes on. If I press the brake peddle the light goes out and the cruise control stops controlling the speed just as expected. If I press the resume button it doesn't do anything ever.

Additional information:
In the winter I have noticed that the set button will work on the first push. In summer it might take 10 pushes. It appears that temperature or humidity has some effect on it. I live in Washington state. Humidity ranges from 65 to 95 percent with higher in the winter.
But the resume button never works, not even in the winter.
The speedometer always works correctly.
The set button never flashes. I have read that when that happens it's an indicator of a cruise control failure. This isn't what mine is doing.