I was wondering what a clicking noise was when I turn on the A/C, and its there when I turn on the Defrost too. It seems to click like something is turning on/off, is there something on the A/C unit that is screwed up or what could cause this. FWIW, I have never worked on A/C units. TIA

 

Maybe debris in the hvac box?
foam seals inside are known to disintegrate
and fall apart with age.

 

Open and pull out your glove box, so it falls forward, and take a look and listen under the dash. Could be a bad relay, or as stated, something stuck and flapping inside the box.

 

Could the clutch on the compressor be engaging and disengaging? The defrost setting runs the A/C as well. Run the A/C or defroster and take a look at the pump.

 

^ What he said. Sounds like the compressor cycling. How often does it click?

 

Clicking is random. doesnt seem to be a pattern to it, but it is noticable. It does sound as if it is about the front of motor though. I know its hard to say without hearing it, but not knowing what/how the a/c works, I think it has something to do with whatever makes the compressor work. Do the clutches for the AC compressor go bad
?

 

It's the compressor cycling. If it bothers you, pull the temp probe farther out of the evaporator discharge line.

They do wear out eventually, but it takes a long time.