2005 Mercury Marquis AC not clutching n

My ac is not working properly I have reclaimed the refergerent, changed the orfice tube and weight 38 oz back into the system, When I turn the system on auto or manual and set the temp to 60 deg the blowers blows out the ac/vents but the compressor does not come on, it may come on in 10 to 20 mins then cycle ore it may not. I've checked the low and hight PSI switches and both are operating, I've check the H2O level and topped it up. I cleaned the condencer coil and raditor. Belt is in good repair cooling fan operates. I have no power issues I checked for codes on the havc control module and also have had the code on the main computer checked with no codes showing anywhere. So what am I missing?