no power at ac compressor

If the refrigerant pressure is too low the system will shut itself down to save the compressor from being damaged, bridging the low pressure switch momentarily tells you if the charge pressure is low After that you are looking at tracing the wiring to locate the problem after that. There is a company that independent auto repair shops "buy" their information from that offer a very reasonable service to do it yourselvers. You can get a one week subrcription or year subscription very cheap. The information is year make and model specific repair procedures, service bulletins, component locations, wiring diagrams ect.... great quality information same as the professionals have ,much better than generic workshop manuals from parts stores, much cheaper than the factory manual try http://bit.ly/mitchell_repair_manuals_online and get an online repair manual subscription.