A/C Lines ??

[71-SS350]

With the Chevelle close to actually doing the painting I am wanting to clean up the radiator support. Can't get the pictured A/C line to come apart where the screwdriver is pointing. Have the threaded nut loose and pulled back, problem is the line won't seperate at the connection. Have tried a gentle twisting and tugging motion with no luck. Anyone had this problem with their A/C lines before? Maybe PB Rust Blaster and heat? Not a torch, maybe a blow dryer on the low or high setting? Don't want to melt the line, LOL Any ideas ??