AC not cold out of dash

[Jsherwood6466]

It's a 1999 1500 Suburban with dual ac. System is charged, rear air blows cold but front dash vent air only gets slightly cool when revved to 2000 rpm, otherwise neutral. Blend door is working, i'm stumped. any help is appreciated

 

[zora]

Have you hooked up gauges to check state of charge? If no gauges try buying a DIY kit and add 1 can to see if that corrects the issue.