Both radiator fans doesn't work

[Kiss Me Deadly]

Hello!

Please give me an advice what to check to solve the problem:

When I turn on A/C, both radiator fans doesn't start to operate.
When cooling fluid temperature raises above normal neither main nor secondary fan starts to operate.

I've checked all of the fuses under the hood and inside the car - they all are ok.
Relays under the hood looks okay, doesn't smell burned - but I didn't check them properly (how?).
I've measured voltage on fans connectors - both are getting 12V on one of 4 wires in the connector when car is running.

Additional information:
There is a leakage in air conditioning system so probably A/C doesn't work at all already, but the compressor starts to operate for a few seconds and then turns off when I turn on A/C. Anyways, before it was recharged (was empty) there was no problem with fan.

I assume that there could be a problem with water temperature sensor, but why then fans doesn't turn on when I turn on the A/C?

How to check CTS? What if I bridge its connector, should main fan start to operate?

Thanks.