AC and other problems

2001 Dakota 100K. AC only cools down to 75 deg. F. Put in a 19 oz. can of freon pressure on my cheap gauge shows about 60. What do I do next? Also Just replaced blower motor resistor block and pigtail because they were burnt up. Now I keep getting a fault code (p0601) ECM failure. What gives? Are any of these symptoms connected. Help is appreciated as it is hotter than he!! here.