Trying to recharge A/c on 2000 Honda Odyssey, can;t get the compressor to click

you dont need to. when there is 20 lbs in the system, it will come on. if it does not, then there is another issue that is preventing the compressor from coming on line. Roy

Once the system sees pressure it should engage the compressor clutch do you have a workshop manual? There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online