When on the clutch is engaged and condenser fan is working and cool air comes out . Sometimes when it stops it does not come on on its own may be for hours. In that state I checked the voltage with respect to ground at the ac pressure switch in the front of the car at both sides it reads about 5 v . However when I force the voltage to ground via a safety 20 Ohm resistor every normal function is resumed .
There must be a temp sensor may be in the cabin ,may be at the evaporator that does not send correct temp info to a controller somewhere , I ThInk !
Can you please guide me . I can't afford new car or hefty repair cost . I have checked all relays and fuses already .

 

when it stops working, see if the evap lines are freezing over