I have a (new to me) '99. The A/C adjustment is manual and I run it at full cold. When I operate in warm but not really hot weather, there is a clicking noise from time to time. When the weather is hot, there is no click. Is the click from cycling on and off? Is it normal or is repair needed?

 

It could be, but the clutch in my '99 is very quiet so I can't ever hear it cycle. Of course, it could be my ears...

To check, this is what I would do. Switch between A/C and Panel and back again. This will turn the compressor off and on. If you hear the clicking, it could very well be the compressor. Now, do it with your window and hood open, especially next to a concrete building or inside a garage. Is the clicking louder? If so, I'd be fairly certain that it's the compressor's clutch that's clicking.

 

Pop your hood, watch your AC compressor clutch engage and disengage (the center spins or doesn't spin). See if this correlates with your noise. Some clutches are louder than others. Worn out clutches make can make all kinds of noise. If it engages fine, the noise is minimal, and your AC functions well, it's probably ok.

 

i was experiencing the same thing with my '99, along with condensation dripping down. i got worried and went to the dealer. apparently, newer vehicles run the a/c here and there to keep the clutch from freezing up for the months you're not using it... hope this helps...
sometimes your local ford dealer is a hell of a lot more helpful than some of the people on the internet. it never hurts to drive down there or make a 5 minute phone call. (i've got 'em on speed dial)