Clicking Noise coming from dash when heater on cool air

[autobody]

For some reason, when I turn the heaters on I get a stange clicking noise. Like a relay moving, or something adjusting.

I have a Import sc with climate control and AC.

The sound only happens when I move the temp switch from 30 to between 20 and 25 on the heater panel. I don't get the sound when on the coolest temp. There is no air in the system and I don't get the sound of water moving. It's a clicking sound which does eventually goes away after a min or so. So sounds like something is adjusting. If I move the heater to 22 it will click for a min then stop, and if moved again to say 24 it will make the same sound then Stop after a min. If move anywhere in the +25 then there is no sound.

Everything works fine, the air does adjust and goes from hot to cool no problem. And cool to hot fine.

I did have a heater issues (not working on low speeds, only on high) which is now resolved but I think this was there before and did not notice it much as the heater on full is louder then 1st speed. It's just a very annoying sound. Any ideas what that might be?

The car has been stood still for over 4 years.

[jimi]

Not all that familiar with how the MK1 AC is controlled, but I do know that on a non-AC equipped Mk1 if you press one of the ventilation control buttons then the change is achieved by a motorised flap
i.e. if it was set to windscreen (right hand button) and I want the heat to my feet (middle button ) pressing the button causes a motorised flap to move to redirect the air
I suspect that the noise you are hearing is probably a motorised flap moving to alter the balance of cool air to hot air in response to you requesting a different temperature.
I think I have some drawings showing the AC controls, I'll have a look later and see if I can confirm my suspicion.

[autobody]

Thanks Jimi, the heater control looks similar to the non AC and climate control.

Here is one from the web. http://www.basirk.com/mr2/se/images/ac_climate.jpg

I would assume they are very similar in how the hot or cold it is adjusted.