Air conditioning turns on and off, it works weird

I have a VW Lopo 2005, but it seems that it only works when the fans turn on, that is, when the engine is heated and then the AC cools the interior, but when the fans do not work, the AC throws hot air, what problem does my car have?

Check the gas pressure and evaporator valve.

Look at your problem can be presustatic valve found in the filter or in the diffusion or high spartern that happens that when you turn on the air you must work the direct electro but with low speed it also reviews the reflex are two one of high and low the low one has to look for it because it is not doing the power pass to light the electros