I noticed recently that when my air conditioning is on, I would sometimes hear this cyclic clicking noise. Click ...... Click ........ Click .... etc..

It was really annoying.

So I popped the hood and tried to find out where this clicking was coming from.

I then noticed that the lower pully (AC pulley?) has 2 concentric rotating parts. The outer part where the belt touches and an inner part. I was watching the pulley and suddenly there was a click and the inner part which has this triangular part attached to it stopped rotating, however, the outer part continued to rotate with the belt. Then a minute or so later the outer and inner part rotated together. Then a minute or so later, the cycle would repeat it self (click .... click ....).

Most annoying.

Does my car have a problem or is this normal?

Most annoying indeed.. mine does it too. AC on, top down = problem, I have to turn up the radio to drown it out. Top up, it doesn't really bother me.

But this problem bugs me a LOT more than having to turn my gas nozzle upside down - I wish Ford would step up with a fix for this annoying click. I would give up my car for a week in the shop to be rid of this annoying noise.

I think we're supposed to live with it though..

It's normal. Your A/C system has a pressure switch that disengages the A/C clutch when the pressure reaches a certain amout then turns it back on when it drops. The large outer ring that the belt rides on is just spinning on a bearing while the center part that you see stop and start moving is connected to the compressor via a splined shaft, veiw it as the driveshaft for the compressor. But anyway, everyting is working like it should, you'll just have to learn to live with it.

Edit: if you see a plug on the top of the compressor thats what does the "work" that plug is connected to an electromagnet for lack of a better word. The magnetic field pulls the cmall center part against the larger outer section and esentially "locks" the two together.

But why does it have to click cyclically !!

I don't remember my 94 GT doing that !!

My car does this too. There is a thread on Stangnet about this very issue, search "strange noise." As I have been told it is something normal and just deal w/ the clicking. Very annoying indeed, but if the A/C is acting normal I'll deal w/ it. The noise only comes on when the A/C is on and every 10-15 secs for me.

The reason that is cycles is so that it doesn't build up so much pressure that it blows your lines and other things apart. Your 94 did it, I guarantee it, its just louder when things are newer. Your 94 may not have done it as much because like all things, stuff wears out, therefore your compressor had to run longer to build the same pressure.

Both my stangs do it (2000 gt and 2003 cobra).

The hotter the ambient temperature outside, the less it will cycle. In arizona in the summer months, sometimes it never cycles.

I noticed this before and it's annoying. No other car I have owned makes a noise like this. It has to be some sort of defect or a poorly engineered A/C compressor.

Why does it have to be either spinning or not spinning - makes no sense.

A continuously adjusting compressor would be preferable.

This is how ALL vehicle a/c compressors work, from kia to bmw to ferrari. Some are quieter than others, but they all work the same way with a clutch.

It also will do this when the defrost is on.