Was running fine and one day it just went hot in an instant. Checked refrigerant and gauge says mechanical problems

 

well not sure how a gauge can tell you there are mechanical problem. Do you hear/see the compressor kicking on? Did you check fuses/relays? Any blinking lights in the REC and AC buttons (which flash when the climate control computer senses a fault). Best to also take a look at the serpentine belt as well just in case...

 

Does it stay cool for the first few minutes when you turn it on and then goes hot? if yes it could be a problem with the clutch which needs replacement/re-shimming. I had a problem with my 2005 S40 which cooled for 5-10 mins and then stopped which i solved by sticking bread clips in the clutch (Have to do it the proper way by getting the clutch off but its been working since two months so i am not too worried especially with the winter approaching i wont be needing cool air). If it stays hot from the start it could be something else.