You should check all fuses and relays...
When I romp on my accelerator twice, to engage the kick-down switch, I blow the fuse that powers the a/c circut.
and then the a/c blows HOT, most likely because there is a fallback system... if you loose a/c, through blowing a fuse, the MB engineers thought that it was important to be able to defrost the windshield?
If that doesn't do it then do not try to charge the system without guages...
I tried and had some problems.