If you overcharged the system the high pressure switch will kick the compressor out. if your fan is not turning on then the condenser coil will get to hot and then the pressure goes up and it will kick out. there is no expansion valve in a automitive air conditioner it is a metering device and it could be plugged possibly. get your fan running and then start all over by dropping the charge and ad 1.5lbs through the low side with the control on max cool. see how that works. the low side is the blue cap. check the specs on your car for exact weight to add but 1.5 lbs is a good start