Placing the a/c system under a vacuum causes all the air and moisture to get pulled out the system. When you pressurized the system with air already in it cause less Freon to enter and reduces cooling efficiency or at times not at all. This step can not be skipped.
It looks like you got a leak. Place the system under a vacuum with the a/c manifold gauges connected and after placing the a/c system under vacuum for 15mins shut off vacuum pump and let the system sit for another 15mins observe gauge reading it shouldn't drop if there is no leaks.
To check for leaks pressurize the a/c system with Freon then make a soapy solution with dish soap and water and apply around all joints and fittings even the service ports with a large brush. The condenser can get damaged by road debri like rocks hitting the condenser, so check there also.
Monday, September 16th, 2013 AT 5:31 PM