Hi, I have a 91 Turbo SW20 with a 3SGTE engine. I am having an unsolved problem with clicking sound when A/C is switched off when engine started. It stayed on clicking as long the A/C is not turn ON. It goes away when switched ON. The indicating light on the ECO/ON switch on and off with the clicking sound and stayed on when A/C is ON. No problem with the climatic controller it varies the speed of the blower accordingly with the setting of temp knob position.
Also found the relay at the front fuse/relay box, one of the relay keep clicking and goes off when A/C switched ON.
Read in other forum, someone have similar problem and fixed it after replacing the ecap in the control pcb attached beneath the blower. I have it removed and replaced all the ecaps on the pcb, yet problem still not solved.
Appreciate if anyone can help.......thank you.

Looks like nobody have encountered this problem. 

I have no idea but maybe if you try switching fan off or to speed one rather than auto and listen where clicking is
coming from. This process of elimination may lead you to a faulty component.
Does the air conditioning get properly cold when it is on ?  Plenty people just leave the air on all the time.

Did you end up fixing this?
Having a similar issue myself